The Model Engineer and Amateur Electrician: 1904

20 January 7, The Model Engineer and Electrician. draughtsman, and for three years with the same company as assistant architect and surveyor, cingaged in civil engineering, land. surveying, road: making, oe 1 eral railway estate and “He oined the Staff of Tus Moe. ENGINEER in 1901, ana is now senior Editorial assistant. His speciality is model locomotive and steam engine design, and he has done a good deal of consulting work iin this direction. Mr. T. H. Hawley dates his be eee with and during the early eighties spe cossiidly took part cycles back to the days of the > n old ‘“ boneshaker,’ ible i post. Mr. C. F. Townsend, our consulting chemist. Jat Merchant Tay lors’ School, University College, London, and Chasing Cross fa where for og y Professor C. School, was assistant to the late evan in the chemical laboratory Royal College of Physicians, London. Charing Cross, Mr. owasend oe { 5 arc. Me late Dr. t University aml excellen a Of recent years he has given his time aJmost ody = technical journalism, his forte being motor design nd construction, in which subject he is recognised The motor designed by him for as an authorit his series of articles he M.E. in connection with now appearing, has attracted considerable attention in the trade, and forms the basis of quite a number of 1904 patterns. Mr, Alfred W. Marshall served his appecniie D. ship with the old- established! firm of Mes: Napier & Son, of Vine Strect, Lambeth, oncesongs for printing machinery and coining presses, and now in the front rank of motor car enggincers. He subse- quently spent some time in the works of Messrs. narine engineers, and then entered corinne and motors, “oat 1 business with that of the Crypto Works Coupsey, Ltd. After several years active nection with that he joined the es nowestablished under the firm, name of Marshall & Woods. electric instrument making, of the City and Guilds of London Institute. He “has done a good deal of lecturing on mechanical engineering at Westminster and Woolwich, and his practical contributions on electrical matters will e known to our teaders under the initials “ W. cently devoted his whole time to technical journalism, and has contributed to Engineering, the ancet, =renga Chambers’s Journal, the ther papers. Mr. Towitsend is an F.C.S., and a atts of the Society of Chemical Industry, and author of several scientific works. Mr. W.,H. Wilson-Theobaldis our model yacht ing “expert. Educated at Marlborough and. Jesus College, Cambridge, he took his B.A. degreein 1892,. 897. Hewascalled to the Bar at the Inner Temple in 1893. For the last ten years. he has been private secretary to Mr. David Maclver, M.P., but has lately had to give up all work, owing to ill-health. He is enthusiastic cn all matters relating to yachting, both large and small, and has won several prizes in designing competitions. He has also introduced a special set of yacht-de- signer’s curves, which have just een placed on the- market. Prize Competitions. ginal thinker, and has a decided Jiterary talent. He has recently gone out to New Zealand, where he has already found aniple scope for his marked send abilities, but still finds time to oces ge some welcome contrifnatioym to hisold iove. the AL? verak of the MLE. Han.J- hooks. C. Runciman takes c! tment, with what suc lL Hels anativeof News training at vine sch ” eulecgansia marine cngNene works of He then entered Sunderland. the Competition No. 37. For Foreign and Colonial Readers only.—In order to encourage our readers across the seas to let us know more of their modelmaking achievements, we offer a prize of the value ‘“SomE MopELs I 8 : Powell was the first editorial E. Mr. Frank assistant to be engaged on the M.E. indoor staff, and ipo eeoatiat service in that capacity for Trained in th aeWorks of the several North iat ies Railway, he eet ses a thoroughly sound acqupan with modern ene seiite and He is a gifted draughtsman electrical practi in| more Genates: of the art than one, is an ori- He is the author of lfa: Efe is an M.I.Mech.F. and Assoc.M.1.E.E., and is a silver medallist in : 1904. Electric Generating Station, at Marylebone, and ater joined the staff of Messrs. Capel & Co., gas ind oil engine makers, of Dalston, where he held a fothe AEE. our readers and com fe, Sonth the gotne to the Doxford, of G.Ce Railway illustrated by photographs or drawings, or by both.. give a fur- If sufficient entries are receiived, we will we will each iusuceesetal ent sufficiently interesting to insert. will, in this Competition, send goods to the value f the prize, and eachcompetitor should state what form he would of like his being successful. re ceiving entries for this competition will be March ist, L904. Competition No 39.ae prize of {2 2s. is offered for the best d STEAM ENGINE.’ ‘A MoprL Horizontat of £2 2s. is offered Competition No. 40.-—A prize for the best BOILER.” original design for a “ STATIONARY For further particulars of the two latter Com petitions, please refe page 364 of the i of October 15th = 4 The Model Engineer and Electrician. 224 Merely injecting a little -oil will clean the surfaces. March 10, 1904. Model Yachting Correspondence. A Model Racing Yacht. To THE Epitor oF not be doninseed swith thesame class. merevalves are Banter troubleof to faulty feed or bye. ome so clogged, owing They when lubrication, that they may refuse toIf shut their seats the The Model Engineer. I Sir,—Thinking that some readers are interested in model yachting, I enclose photograph of a model racing yacht I have built to good design and lines. The hull is from a piece of pine, the outside being worked first, and then the inside was hollowed out, leaving a thickness of 3- 16thsin. for the sides, and a piece for the mast, 1 in. thick and marine oe was given to coat of A 2 ins. square. the inside, and two frames were fitt should be similarly cleaned . if dirty. Defective compression can to traced be three different ea four ‘cr ie _ oo may the sis. ut be be worn, ton -rings ma and same the Secondly, and finally, cylinder or the piston may . be cracked. ° ES S B (2) © n :® Piston- Hing are not diffi All that need cult torenew. be looked to is that they are -of the same make and size as point in the others. Mr. Jos. Cottam’s MopEL RacinG YaAcutT. (To be continued.) Tue London & North-Western Railway Company is applying to Parliament, in a Bill for the present Session, for power to construct e. — rt railway from a point near Willesden Jun to R the show ground of the near Twyford Abbey oyal Agricultural Socichy, In a bituminous ei gas Producer plant as much aie from 70 to 80 cub. ft. of power gas per brake orse-power hour ; larger engines only require from The deckis also of pine } in. thick, with imitatioa a aus on. The finiis of teak, and carries 12 lbs, ead. Patent steering gear is fitted to the | boat The hull is painted white up to water line, and blue, with gold line and beading, around the this beading can be removed deck. If desired, with ug trouble. tried her on the water, I was pleased to find that she sailed splendidly.—Yourstruly, Annan, N.B. ane Jos. Cotram. HE mileage of passenger trains on the London North-Western railway during the nee half- On e 5 lbs. of coal per brake hor: nay ee by a gas eas which will only feeiuire J neral trains lee showed a considerable dees having been 8,903,192 against 10,497,160. Mr. Jos. CottAm’s MopEL RAcinGc YAcnurt. The Model Engineer and Electrician. March 24, 1904. ; there will a be a most competition announced Mr. Lev ‘ Radium,’ interesting pape by illustrated by lantern-slides, exons: and demonstrations. Saturday, May 14th.—Visit to Chiswick Power Station of London United Tramways Company. The Secretary will be pleased to hear from ie ae who intend joining the party RipDLE, Hon. Secretary, 37, Minaedd Road, “Hither Green, S.E. 267 Carlisle.—Any model. engineers interested in the feats of a local Society are kindly asked to communicate Westmoreland Street, Denton Holme, Carlisle. with Mr. JosePpH PAaRKINS, II, Model Yachting Correspondence Kingston Model Yacht Sailing Association. THE Epiror oF The Model Engineer. Provincial Societies. Tyneside. — On Satu noni March ki members of this Society, by the sth, the Mr. Wilson Bld chief snectianicel engineer of the N.E.R. Company, visited the pecs works at Gist. Assembling at the worksa am a sending herewith a small be ofa portion of the Model Yacht Sail- Association’s oat House at Kingston, your bright and interesting ish I thought would be of some interest to the yachting readers of journal. The picture shows five_of their ten-raters on the lockers; and I can assure you they are five hard nuts that require a lot of cracking.—Yours faith- nearly forty—having divided gentleinto three’,oe each ¥. um in charge of one,of the above men, commencedin the wheel shop, where they were shown the various ee adoptedin the production 6 ft. 10 ins. wheels of of the massive the new ‘‘Atlantic’”’ type of express EORGE BRAINE Covent Garden, W.C. he boiler shops they saw loco boilers in all stages of manufacture and repair, from the first rolling of the plates for the barrel to the finished article ready for its final steam test before The smithing being mounted. department was specially interesting for the many tine examples of work there to beseen: piston heads, connecting-rods, draw-hooks, brake all beautifully 1 P little machining to turn The article. the finished ponderous wheel pneumatic drills to lathes, showed the cope Kincston MoprEL Yacut SAILING AssociIaTIon’s Boat Houses. aes oie what out the smailest detail ina Doe manner, and yet with the greatest economy. peas. ot In the running sheds were found types, and outside we were fortunate enough to find two of the very latest described These were the subject of much scrutiny and many questions as to their details were asked of and as courteously answered by the drivers and stokers in charge. A fitting conclusion to the visit was the splendid Institute provided by the Company for its co ployer: with its Posen Tce lecture-hall, reading-room, library, &c.—all the advantages of which, together with the technical classes heldin the winter, may A PATENT has been taken out for a combination meter calculating machine and automatic press, which, it is predicted, will render disputes between , water, and electricity and the amount of his bill aeny aeie, by simply turning a lever, he —— a card upon whichis printed the sa ae he oxy- acces ene blow-pipe described by M. Bouché in the Bulletin of the French Physical Society has the flame formed by the combustion of ; a Le of one part of acetylene to 4 ofoxygen in order that the explosion may not travel am into the blow-pipe, a jet velocityis required, Company, and of fine examples of their skill, we due to the pressure of a water column four metres in height. The flame melts most metals eaek; it will solder iron and steel. Even silica and 1 tour, which, though apparently very short, nevertheless occupied three hours of their weekly and on fallifeeon lime the free carbon goes to form poriealts of veal and present officials of the 1d. per we accorded to our aides our heartiest thanks for a half-holiday. are melted . With a reduction of the oie poorn of oxygen, the flame becomes luminous, carbide of lime, The Mode! Engineer and Electrician. April 21, 1904. 383 main supply to engine use $-in.—certainly not less, but as much larger as you wish with a bye-pass on the delivery so that the feed can be adjusted by turning the excess of water back into the feed tank, and if ake make a regulating valve whicl e steam will actuate a down or increase the oil supply as the [10,687] Testing Boilers… F. H. H. (Bampton) writes: I have bought a vertical boiler and engine, and I would like to test the boiler as it seems rather Is it possible to test it with t find the steam” engine very much trouble with the driving belt engine pump driven by the flywheel, and also could you tell me where to look fornceiegis gas engine will pro ve. far whet testing ond should I test it to twice you maytest. by water to about 1 to twice the working the working pe es, pressure, and circumstance. See issues of 15th June, 1901, and2sath we tober, $0) [10,553] Primus ner for Firing Model ideiee bur r, No. o. get an idea of the plate thickn ss by Thes may drilling afte Look to plate thickness at the foundationine? Boiler is a large one, employ aoe H. B. Pe, ee mall Accumu!.ee queries? (1) Can rimus burner be used for firing a model loco (firebox, 2} 2} 2)? (2) Cost, and where obtainable? (3) What is the liquid fuel used in seme (1) Yes ; use a non also ll holes near ph 1903, for further ae on the subject of feed p {Saffron Walden) writes? Will you please answer me the following boilerinspec WwW. W. poinchester) urse of construction, and p: (2) About 12s. ; can be had rope Melhuish & Sons, Fetter Lane, Holborn, W.C. (3) Ordinary p coal Ri ig for « Lugger. . H. (Balham) writes: I have the hull of a Deal lugger {model}, peshould be ver y much obliged if you could give me a roug! tch showing the rig of one of these boats. The scale woul not naltter, because thoughall the Deal luggers are rigge spars, &c. ay owner. Hull i within et the sizes of the v: ndan has a covered hatch. Any further particulars oo I will ser $0 known. voltage. see handbook “Small Accumulators,” 7d. post free. single ain a secondary cell is capable of one ie 2 Vol malt Horizontal Engine. supply drier steam by cone This will make the engine economical and a € the boiler power is limited, hi: her boiler pressure will be maintained and the speed of the engine incre: sone 10,411] u i Mains. J. H. J. (Harrogate) writes : I havea small motor with which I wish to work a dynai in Supply we please give mee Instractions how to make a suitable i i the supply fro! oO 2 ey Pt rmer is practically a motor coupled up to dynamo the one beingwound to rece!ive a high voltage oe oe and the other to yonerate alowv ence, if you ma 12 * why n t Al\ ternating “current fraasformers have been dee with in I. LIN! 105 5\7. New Catalogues and Lists. DIAGRAM OF RIG FoR A LUGGER. Mast, } in. diameter at deck, tapering to § at peak; bowsprit, 8 ins. outboard, , § in. diameter; measurements on plan are for edges of sails; oy na must, therefore, be made for the lengths ofspars. e Power of Petrol Engine. H.T. F. (Bovey d. Hobbies, Limited, 12, Paternoster Square, London, E.C., hav sent us their photographic catalogue for the present year. “ilius. trations and prices are given of hand, folding, and stand fameras. Amongst the last-named isis a camera especially made to hold plates of the p or horizonta lvviews may a 2 i ost-car g apparatus, lenses, complete outs 2ot amateurs and professionals, strok minute ? ow am (2) The number of useful gikes means the number of explosions 33,000 X 12 uring each explosion. The vapour, Sie condensed, forms petrol. Supply Pipe for Gas Engine Burner. st Gorton) writes: Could I ask you what size of gas pipe pp! . engine? tube hot. 4-in. or a $-in. gas barrel would suffice, but for me you m besides chemicals, accessories, Arthur Firth, Engineer | ae Tak maker, Cleckheaton, York- shire.—We have receivved a price list of m:achine tools and accessO, of tt piston oFonly, should not the number ofrevolutions be taken, instead gas engines ani c mo ors and wine sent to readers of this journal upon eceipt of two penny s S. A. W. Roy, lesictent Engin neer, 151, Shields Road, Heaton, Newcastle- on ‘Tyne. ee his list. of various dynamos, armature lamina ions, field- c. L.. For : containing ifusteations and prices Manufacturing Electricians, Market Street, Stalybriridge, send us a list of electrical and ne mechanical apparatus manufacta red by them. prises water motors, dynamo portable accumulators, v issue a separa ‘ate she such as motors an sir telephones, ‘pocket lamps, etc. i i bi ynamos, alarm clocks, miniature The Model Engineer and Electrician. 572 The whole ant takes to pieces and for convenience in packing I have made the track to hingein the middle. In conclusion, I may say that the whole modelis quite original and my own work, only the Lae of the cars as they meet the station is what I remember of the Hastings lift, which first gave me the idea of building this model. How to Build a Feather- weight Model Yacht. y “i Besar: A SIMPLE plan ‘of building a model yacht of extreme lightness, I think, will be of use to any readers of these pages. a style of June 16, 1904. the strain of the mast with its sail is very great ane are quite strong enou g I think if I now explain the figures, I shall better Eee the boat and her construction. —The black lines are the beams and cross- be but $ in. thick, teres, ‘the frames AA should suo be } in., the crossbut the cross beams BB w frames about } in. each The lower part of Fig. 1 shows the first stage, the two planks cut and oti on each other with holes for wire to keep m together to distend fk hull a the a — (dotted lines) are allin place ; dotted line also show method of taking thefin tight through the boat is not untried, for my own boat, Sha built from oe lines last year, headed ‘hes classin club racing. The first thing to obtain will be two pieces SECTION. of ew frame backing about a foot (or less) wide, 6 ft. long; this should be of 4 in. thick, and as free from knots as possible. Cut the wood in the shape of the profile of your boat (Fig. 1); then lay the two pieces on each other and pe small holes (Fig. 1); in these holes a’ coe the sides stronger for the cross beams; these should be about 4 in. thick and 2 ins. wide, and all used to distend the hull. Along the inside at the keel and along the inside at the cutwater, pieces of wood cut to fit should be placed ; they need not extend the whole way, but can be placed a few inches apart. These should be fastened with enel screws, or, better still, with black ping clinched. The hull should have cross-frames as showni Fig. 3, but even another one might be added to the two shown with advantage. The mast beam should be larger and stronger than the other beams, as Fig, 4.—CoMPLETE Boa, SHowING SaILs. boat for strength. The black tinealong the keelis tape, whichis best put on by meansof cycle black. First put the black on the note ieee the tape is to be stuck, then about five minutes after appl the tape (dry), then when stuck give the tape itself a coat of the same black. The hull at this stage should be given a coat of boiled oil both inside and out. the hull; Fig. 2 shows the method of distending the number of beams used will be best judged by the builder himself, the nature of the wood sometimes needing more and sometimes less. Fig. 3.—The sides of this boat are as shown, quite V-shaped, but this, on account of the extreme lightness, is no disadvantage, as would be the case . The fin should not i be more than } in. thick, and putty must be placed inside at the place where it enters the hull. The bulb should be cast in a mould cut in two pieces of wood ; its weight being about 10 lbs. When the hull has been so far completed, the deck must be obtained; this, in my boat, the Shark, consists of canvas with two coats of boiled oil. The canvas should be fastened in the same way as the tape was, but must have a number of black pins, also it must not be oiled until it is in place, then wel shrink it, and when dry the oil may be used. batten must be put around the boat to hide the place where the canvas is stuck to the hull, and also to prevent the sharp side of the wood from rubbing away the canvas when the vessel rubs the side of a pond. 573 The Model Engineer and Electrician. June 16, 1904. The hull is then ready for painting. Sail Plan.—The mast, boom, gaff, and bowsprit should be of bamboo and need not be very thick, as bamboo is of great strength. The sail cloth can be obtained at many places in London at Is. per yard. Holes may be made in bamboo with a sharp awl. I think the sail should follow the drawing as closely as possible. Practical Letters from our Readers. have witnessed much, and would, on no account, disparage, dishearten, or depreciate any enquirer after knowledge.—Yours truly, Newcastle. JoHn Rosinson. The Potentiometer and Volt Box: To THE EpiTor oF The Model Engineer. S1r,—I was very much interested in the two articles which appeared in the M.E. for October 15th, 1903, and February 11th, 1904, on the Potentiometer and Volt Box respectively by Mr. «Je As Iam thinking of making a couple of instruments of this kind, I should be pleased if either you or Mr. Kean would give me a little instruction with regard to the following : (1) What alteration, besides in the gauge of wire, would be requisite in their construction in order that the “line” terminals of volt box could be connected across, Say, 220 volt mains continuous current and f suitable for the potentiometer and volt box respectively ? (3) what would be the range in amperes at could be measured with the combination ? (4) Is there not a mistake in the wiring diagram (Fig. 19), page 375 of M.E. for October 15th, 1903, of the connections of the half-ohm and unknown resistance coils to the compound switch ?—Yours truly, S.C. F. Dear Srr,—In reply to Mr. “S.C. F.,”’ I should advise him to use No. 32 B.W.G. platinoid wire for the volt-box. This wire has a resistance of about 2 ohms per foot, and will carry safely a current of half an ampere without any appreciable {The Editor tnvites readers to make use of this column for the full discussion of matters of practical and mutual interest. Letters ull may be signed with a nom-de-plume if desired, but name and address of the sender must invariably be attached. though not necessarily intended for publication An Electric Problem. To THE EvitTor oF The Model Engineer. DeEaR S1r,—I observe three letters have appeared on this question, and yet the solution seems are driven pumps Where underground far o accident at the resistance end, which might stop the pump or pumps, would produce a state of confusion in the voltage at the dynamo. Theory canmysterious happenings not determine relating to electric installations; an a : Vollmeter. wedi | Mains + = Volt box ¢ PS | Galvanomefer D—- ° P { dL | U2. 9, Lanush M AA & rs Fig. 1. times be explained by the readings of the voltmeter and ammeters ; even the lifting of a brush ooden under load does not often cause a flash. handrails are preferable to steel in all cases. ‘‘ Enuirer ’’? must live and learn. No man without a full knowledge of the facts peculiar to any given case can offer an accurate solution. There has been, and will continue to be, cases which baffle heating. To find the resistance of the volt-box wire under the given conditions— R 220 “>: =440 onus, Hence 220 ft. of No. 32 D.s.c. platinoid wire will be required. Then referring to Fig. 3 (page 113 February 11th), the resistance between terminal E and F being 440 ohms, the resistance between E and C must be 4°4 ohms (about 2:2 ft. ofwire). The p.p. between E and Cis, therefore, Failing this, there will, I guess, at times be flashes at the dynamo, which cannot be measured. I 220 2°2 volts, 100 . 7 which can be measured on the potentiometer. 594 The Model Engineer and Electrician. June 23, 1904. be rabbited out to receive the deck. Give the hull three coats of paint, each one being es see down with glasspaper, and two coats of mel and My llodel Yachts. By H. A. Taytor. O construct the steam yacht illustrated here- ae (the enamellingis best left anti!Saath Dimensions, oe ees are 7 ft. long, 10}-in. beam, 3 ins. dee entre, I0 ins. at bow and stern, the hole for propeller is 54 ins. by 2} ins. Other details can be gathered from the photograph which show its lines fairly well. € engines are made entirely of gunmetal and steel, all nicely turned and well fitted (see Fig. 3). The ere tis made from a piece of Bessemer steel, 1 in. by 4 in. by 8 ins. long; this is marked out and holes driiled all round the cranks and the pieces of metal cut out, it is then made red hot and the is to go and eas about } in. off. by 4 in. Now place a narrow strip on the opposite side for the keel—see eeit is quite straight and in the centre cranks twisted to right angles, centred at the ends, and the shaft turned to # t a made aa tis to turn the crank pins ; made piece of the same metal drilied f3 in. is take the ote Fic,1,—Mr. H. A. Taytor’s MopEL STEAM YACHT. —then saw off the corners of the block leaving } in. for finishing, then cut a templet to the shape of the hullin the centre, whichis nearly square, as will be seen in Fig. 2. ‘Now sha: ape the centre to the templet; after thisis done anyone with fairly good eye can shapethe bows and stern sufficiently well without templets, but these may help ‘When the hull is roughed out e planks with a saw leaving } in. all round peeoe| at the ends, where it is best left solid for strength; of course, the bottom one will have to be carved, or drilled out. Then see that all the joints come up close when in the hand-screws, as they should do if they have been planed up with a trying plane, but if they do not, shoot them again with?aeee plane, then glue up, and finish off. of bra in. by } in. is now let well y 4 in. extending from bow to rudder post is eens on the whole length of keel. The rudder if made of a piece of }-in. sheet brass, cut and filed to shape will make a strong job. Now mak thick whitewash and rub it well into the wood; this will fillin the grain and make a good surface for painting, &c. When it is dry, it should A Fic. Strife of Brass 2.—SEcTION oF HULL. of the shaft, cut with a saw, and fitted with a setscrew to clamp it. Then mark off the centre of shaft, centre and clamp it in line with the pin to be July 14, 1904. The Model Engineer and Electrician. afterwards filing Ki shape, a triangular file being The een Stole (Fig. D), is somewhat more aifficult to make, the filing of the six sides or flats parallel, and at the same time keeping the angles correct to soe a symmetrical hole being by no A WRITER in the Aluminium Wo vlad eives the constituents of a hard alloy which has means an eas After cath ine off and drilling the circular hole in the same way as with the other shapes the diameter of hole Lees the distance across from one flat to the 33 Aluminium Alloys. useful for fini or steel and nickel-plated, eye heavily, the plating soon wears off, leaving the metal site one, a square fileis intro- duced, a little less a width than the width of flat of hexagon, and after filing one flat the opposite one should be similarly treated, proceeding in this way until the six flats have been filed. As a rule, the diameter of the io hole may, with advantage, be made a little more than the width across the flats, the slight pov left by the drill along each flat being useful as a guide when filing to shape. My next article will deal with the methoa of drifting oF punching angular holes, and a descrip- tion will hole. be given of a method of drilling a square (To be continued.) A First Attempt at Model Yacht Building. By G. T. *Riawemics, T Lsfe ape ays is of my model yacht, HE photograph (Fig. Sececea are :—L.W.L., first 2) accompanying this ae t The leading ; breadth, 64 ins.; baie gee ae ins. It is cut cos a wood, ich I m beymote1 engineers like myself, is somewhat liable to split, although it is easy wood to work, Fic. 2.—Mr. G. T. Wirttams’ Mopet Yacut. underneath exposed to rust and corrosion, a condition which, of course, is not permissible. If the Vi Fic. 1.—KEEL Conaeueviow «- haa G. T. WitiiaMs’ MopEL Yac ag keel, shown in Fig. 1, is, I think, original, it is designed to take off when required, to ver,” or “silver metal.” even as follows :— The proportions – Nickel i Aluminium This alloy sy . ts ei ++ 57.00 »+ 20.00 20.00 3.00 when used onn typrewriting machines is firmly fixed. The upper halves are Rey et holes in the bottom and in the dec In my boat nickela. mage for the sake of the first appearance ened up through a square hole cut out of keel, and clearly shown in photo ; but, if any reader should are of a character that recommends there is one bolt between the rods,ie is tight- think of copying this, I ‘would strongly recommend him to do away with this bolt, and fit instead two nuts on the ends of rods above the deck. In this case the deck would need strengthening a little. By now fitting small washers between keel and bottom of boat and tightening up the nuts on deck it will be found to be very rigid and quite watertight. but are ; ¥ as corrosion is concerned, nickelling is wane cesaEEy Inregard to its other qualities, they the alloy for i The liquid metal completely fills the mould, giving sharp, clean castings, true to pattern; its cost is not greater than brass ; its colouris silver white, and its hardness makes it susceptible of a high polish, 69 The Model Engineer and Electrician. t a SPARS. at nz 9 ofof Deck De Tor c i Seen about > July 21, 1904. ee ere el =p Pe 3 a J Booby 3 a Sat me oe < Gunwole——— er —" oo For description] A DESIGN FOR July 21, 1904. 61 The Model Engineer and Electrician. ee rR Foremasl Mainmast | LINES UBLESTANDING LUG. TES Key =— [see pages 62 to 64. 62 The Model Engineer and Electrician. A Model Double-Standing Lug. By S. J. THompson. HE double standing lug July 21, 1904. on both sides of the block, and a light batten e wood should be sprung to touch the marks an pinned in place; the sheer can then be marked a I am about to de- lines and sail plan ar lug which was renowned for her fast sailing qualities. As a start, I may aaa we made two hoats from the accompanying drawings, and sailed them on Hornsey Mere, near Hull, where the little craft the block should be joined again by marking them in, and the centre line reinstated where cut away 4 O47 SeCALE ge LE 2 (i777 Fic. 1.—Tre Sar Pian. used to sail across a half-mile stretch in twelve minutes, notwithstanding there was a considerable sea on. hey were cut out of blocks of pine 27 ins. long by 8 ins. as by 44 ins. deep, and hollowed out so as to have, when finished, a thickness of } in. as uniform as possible. The process of Sed is as follows :—Plane the for the sheer. The half breadths of the gunwale line are now to be spotted in on the ordinates; the batten must then are next roughly sawn off. The above cee The corners of the block should now be cut down block all’over, except th ody plan. Care shod be iglen toon on every aol the marks W.L.1. adde The sheer is best marked out on the ordinates and the gunwale. he quickest way to prepare such moulds is to trace by hand with a sharp pointed pencil the body section to be dealt with to lay the tracing on the cardboard, and prick it through on to the cardoard. The spots should then be joined up by July 21, 1904. The Model Engineer and Electrician. pencil, and the mould carefully cut out by a sharp poin nted penknife. When all the sections are finished, the model should have two pieces of wood 63 till the blue chalk on the section marks all along the groove and fe els and W.L.I. marks are same side of the boat aed then be treated in the the same 1 screwed to the deck so that it can be fastened to a table, mould or bench, with the keel pointing to- other sections on other side treated in exactly the same wa which the boat is inearewet from the bench and well sandpapered. ‘he next thing to do is to hollow her out. I usually centre-bit away a considerable amount of the inside taking care not to cut too deep. Rough inside moulds may then be made by laying the outside moulds on the top of a piece of cardboard marking the curve round by pencil and allowing a thickness of | in. for the thickness of the boat’s spin. The mould will then appear as Fig moulds and fitted inside the boat, each at its proper station. The keel I cast of lead, making the mould out Tic. 2M. S. Je THOMPSON'S “Move UNDER unwale SAIL Fic, wards the operator. Now take the midship section mould. This should be chalked with blue chalk and fitted 3.—OvurtTSIDE Mou_ps. to the midship mi section ordinate scribed on the block by paring away with a gouge TABLE oF OFFSETS. Sheer | Nos. on | Body Line. WL + Breadths. from Gunwal> | W.L.I.| Line | | toU.s. + | Deck at | Breadths. | Side. | ins Ins. _ W.L. W.L. ins. Ins. W.L. 2 | I 332 BE ve 2 34% 135 4 3 33% 248 ve) 8 ins, | Ts | oak te | Ws — a ~ Te 4 3a 5 3b axe) ot 3k ak | 6 3y5 7 376 | 348 33% 8 | 3k ok 9 | 2 ay | 288 | 3su i ad 3n% | 388 | je ao 235 |e ~_— 253 ne ~4 [Outside ‘Shin.of ship at Fic. 4.—INSIDE”MouLDs. of a piece of board, the contour of pe upper and lower edges being got from bs drawing. The face which lays against the boat 34 i} | Distance between I. Sagi Sections S 34 ins. Distance between Water Lines { in. extreme ends I spiked Hagatalty: sev ing. carefully drilled the oh for the purpos é e rudder, which is of brass, TI next fitted, and The Model Engineer and Electrician. 64 may explain that the two helical springs are for the purpose of keeping the helm amidships. The main sheet is.rove through two quarter blocks, and hooked to the tiller, and arranged so that the harder the main boom is set over by the wind, the more the tiller is pulled thereby up to windward. The everage of the tiller can be adjusted to suit the wind July 21, 1904. Aluminium and Alloys. By CLARENCE E. WOODEN. N moulding aluminium, use the sand well burnt, nd work it as dry as possible. The gating on heavy work and the use of risers should be about the same as in brass; but on light work a wide, thin gate should be used, and on very light plates, where this kind of a gate does not run the castings, use a flat sprue as used in the stove foundries. The cores used in aluminium should be made soft, viz. : flour sand cores, rosin sand cores, It is not advisable to use @ an oil sand core, as there is not enough give, and they very often cause the casting to crack. Aluminium does not eat into the sand enough to use a facing, unless one wishes to, although I have used charcoal facing. When melting, never overheat the HAL Brass Spring Z \\\| V2 20 SWG fo is the metal melted before the moulder has finished his moulds. Main Sheet Fic. 5.—RupDDER. by shifting the sheet hooks. I This arrangement hanging the gunwale 4 in. all round ; I then lined it all round i ships than at the sides, two of them being fitted close to the holes for the masts. To insure the deck being tight round the gunwale it should be painted when lifted underneath and pressed into place;places on the it will leave paint on all the high gunwale; this should be repeated, and the paint planed off till it fits all round, when it may should be well varnished-and the hull given two coats of enamel before sailing the boat. A Lone Tunnet.—Another long Alpine tunnel is hi pleti This is the Bosruck being driven tunnel, 4,760 metres in length, which is new railway a mountain range to give a through connection from Bohemia to the Adriatic. Work on the tunnel was begun in 1902, and it is expected to have it completed and the line ready for traffic in October, 1905. Fic. 6.—-STEERING GEAR. To hold the metal or overheat it is very injurious to the metal, as it absorbs the gases ; never pour it hotter than a cherry red. Just before pouring, if a little phosphorous is stirred in it helps the metal to run better, and gives it a slight bluish tint; rosin can be used also. If poured too hot, it will segregate in the mould, and will also cause num berless pinholes. When the metal is polished, the holes tear and give a very bad appearance. This trouble will be found more often where copper is used as hardening than where zinc is used, but will happen with either if the temperature of the melted metal is not kept down as far as possible. Some toundrymen use tin as a hardening ingredient, but the zinc is the cheapest and gives the best results. Tin makes the metal very brittle, and if too much is used, it will crack in the mould or shortly after being shook out. Pure aluminium is a comparatively soft metal, and has many of the properties of copper, and when this metal is used the best results are obtained. Very often the metal is im- pure, and poorer results are obtained by using 160 7 The Model Engineer and Electrician. ee equal ; Model Yacht Architecture. ward ’’ By W. H. Witson THEOBALD, M.A. WING to the rapid strides madein the pastime of model yachting there would appear to be an opening for giving to those model yachtsmen who design their own boats?an Gaon ey for fur pe increasing -their knowledge in the art the usual rough and sa | methods August 18, 1904, is to say, the pressure of the water must be equal to the weight or pe wen of the boat acting ‘‘ downward.’ number of forces acting on a body can be fohiigal as they exactly counterbalance of coraaallegflies various centres, &c.; it is hoped one a they must be acting in the same some study. forces acts is called the ‘“‘ centre of buoyancy,” and that of the dow nward forces the “centre of gravity of the whole mass also that those entirely ignorant on’ the subject may be sufficiently interested to give the matter ae CENTRES OF BUOYANCY AND GRAVITY, AND METACENTRE The dog nccemers of a boat is the seiohit of the volume of water displaced by the hull, when the latter is afloat in full trim, and this weight again is exactly equal to the weight of the hull and gear. is is a most important point to remember, and to further explain it an imaginary case will be taken. Supposing that a model, fully equipped for sailing, – placed in water; and let it be assumed possible at the water all round is one and the model ne withdrawn, leaving ity of the exact shape and size of the iilee seater body. Now, if afterwards poured off and weighed, it would be found that its weight was exactly equal to the weight of the boat. vertical lin e home at which the resultant of the upward The centre of gravity always a through this resultant point, no matter what e position, or heel, of the boat. This is obvious are it is remem- oncrete mass which never alters its shape. It is quite possible, however, for the centre of buoyancy to be shifted forward or aft, or to port or starboard. In the ne of a mechanically driven hull, assumed to be running without side heel, at right angles to the direction of the flow thewaves, a position would be possible. ow, suppose G to be ie position of the centre such asis shown in Fig.1 of gravity of the hull, and therefore in the a vertical line as the centre of buoyancy when boat was resting on still water; in the ilivotration it is clear that this latter centre is no longer in this hy and then, by carefully putting the model in the water, a certain amount of the liquid will be forced, or displaced, out of the smaller into the larger; if then this overflow of water is weighed it will be found equal to the weight of the model. © For the purposes of model yacht designing linear measurements are taken in inches and tenths of an have dived considerably, and the sudden support given it by the next wave would have thrown the B wv G Fic, 1. be greater, and this can only be obtained by the boat sinking lower – the water. Asa result the model is not floating on the designed L.W.L., but deeper ; and the iasboand is diminished. Of couurse, a little trimming inside ballast is a different matter alto- gether. The only possible way of increasing the srahi ey of a model, and still maintaining the same water a false keel, in both instances keeping to the original total weight. When a hull is floating in dead still t work, one the preventing this tendency to sink. As th motionless, it is obvious that freee two forces must centre of buoyancy forward of the centre of gravity, and then the Peeing of the centres would cause the bow to rise. Hence the the stern to sin unpleasant slinging and ascending motions of a ship is ae waves. Excepting for sea-going models, this fore and aft carcely be taken into consideration, motion — s formed on a pond are barely sufficient to affect any model of more than 30 ins. water-line. asa ‘guide to the stability and sail carrying power. This will be discussed later on uoyancy is a guide The position of the centre of bu to the relative fulness of the fore and after co Everyone knows that these two portions of a boa aay are not similar, the after part being almost for finding fuller than the fore body. Calculations the positions of the various centres will be given; The Model Eugineer and Elestrician. August 18, 1904. meanwhile it should be noted that the centre of buoyancyshould not fall more than about *o5 of 161 find the position of the centre of buoyancy when heeled. Arguing on the same principle as the boat amongst waves, as the right-hand side of boat has been increased and the left side decreased, it follows that the new centre of buoyancy must have been shifted to some os on the right-hand side of the the L.W.L. aft the centre of the L.W.L. In other worl: if the L.W.L. is divided into twenty parts, the C.B. should be situated so that eleven spaces areee and nine aft of thecentre. As before mentioned, knowledge of the position of the centres of buoyancy and gravity are neces- centre line A Rules for findingal these centres will be foundin And now there are two forces, the weight of the a later chapte A boat still acting through G and at ao angles to the level of the water as through PG, and the pressure of the water acting upward th ough B’, and also at right angles to the water tenet (and ie ~ hence parallel to G P) as M B’. In the old-fashioned models, placement in the shape of lead with sometimes on the centre of gravity ae often ann above the centre of buoyancy. This would have slightly altered the drawing; but at the present time, with lightly constructed hulls, this contingency need scarcely be provided for. Through G draw GS at right angles to’G P, and meeting M B’ produced in S. GS is the length of the “righting lever,’ aa this length pg ee by the displacement in Ibs. gives the righting moment” of the hull in inch-lbs. at the given angle of heel. Fic. 2. sary in estimating the “‘ righting moment ”’ cf the hull, and, consequently, the sail carrying aed a the model ; and this calculationwill now be ta Fig. 2 shone the section of a model heeled te cea degs. A sailing. Let B be the centre of buoyancy of the hull whenin an upright position, and G the os of gravity of hull, &c. (this latter centre, it . must be remembered, does not move its position under any circumstances), L L’ is the surface of the water. It will be seen that, when heeled, the portion E F H of the section has been taken out of the water, whilst the poynen F «J has beenLay in. “in”? wedges. Ns a called the “ou oesat initial stability. Narrow boats, on the other hand, are easily heeled from the perpendicular, but have great righting moment when a certain angle of heelis reached. aving found the righting moment in inch pounds at any given angle, it is obvious that the moment acting on the sails will heel the boat same This will be treated on in the to the same angle. . article on sails. Centre of gravity of “in” and “ out ” wedges.— When a boatis heeled over by the wind, it has been the curve of the eethad heen circular, Gaeweney not only shifts to leeward, but, owing But the section is bers So; and the ‘“‘in”’ aft direction as w it isether that these two wedges would have been equal. The point of intersection of the original perpendicular A B and the line S B’ through the new centre of buoyancy is called the ‘‘metacentre.”” In broad, shallow boats the new centre of buoyancy, when the hull is heeled, moves very rapidly from the centre line, and hence the righting lever GS is ae and the righting moment large for small angles Such boats, therefore, have what is called wedge is a than the ut.” ow, from what has Besa:said about the displacethe amount of body below water, which is the same ee —— asa thing as increasing | yee ” wedges must ‘ and matter of fact, the ‘‘in’’ – equal, and to make chen aaa it is necessar line, until it is jue by trial that the two wedges the the require to be drawn below new water level vailmeans that when heeled, a boat are equal. “in ’’ wedge is the greater, original one, which rises in the water until the under water body is of exactly the same size as whenin an upright position. a new water level which gives, aving found approximately equal wedges, the next step, is to inatio to this alteration sa! form, often moves in a fore and ow, it has been shown how harmful to the trim of a boat this shifting of the centre of buoyancy forward and aft, with reference to the position of to remedy this defect as much as possible. Inex- periencedAesienurs are apt to take immense trouble over the fairing of the under water body; whereas, as a matter of fact, the topsides, which form the head, or stern when sailing at an =e it is necessary that the centres of gravity of the * and ‘ wedges should, as nearly as aesvtile,‘fall ii n the same transverse section of the hull. In: practice it is , 162 The Model Engineer and Electrician. found difficult to gain this perfection, the centre of gravity of the ‘‘ in” wedge being generally situated e August 18, 1904. A Useful Milling Spindle. In straight stem By WatterR K. FIELD. DESCRIPTION, together with a photograph a e designer, therefore, cannot be too careful — fairing the topsides of the boatin so me hull aeof the “out ” the fore and aft a (which will, when the as to ensure the wedge), is heeled, form the “ in’ 66 ey it. All who do small and accurate work would greatly feel the benefit of a similar tool. The fo) ollowing are some of its uses and advantages f desig :—For drilling spoke holes in cycle hubs, or wath 3at an angle; putting keyways and slotsin Fic. 1,—Vir. WALTER K. FIELpD’s MILLING SPINDLE, SHOWING LAP, PLUG GAUGE, AND REAMER, FINISHED WITH THE TOOL. centres of gravity of the wedges a a as near as is possible in the same transverse section (To be continued.) IESEL ENGINE Trst.—During a recent fuel consumption test of a Diesea1 EMBED of 160 brake horse-power output, the consumption of 0°37 lb. of crude petroleum per horse-power per hour was obtained. Withoil at 42s. per ton, this is equal to one-twelfth of a penny per brake horse- power hour. UMBER OF Motor VEHICLES.—In his paper on “Motor Vehiclesin Relation toMunicipal Sorvice! j Engineers at Glasgow ns “Ye E. Shrapnell read before the Conference of Smith stated that the number of motor vehicles registered in the country, so far as figures were available, was 18,340 cars and 21,521 cycles, whilst about 58,000 driving licences have been issued. work held between centres; grinding grooves in g reamers, taps, &c. square, &c. It can readily be raised and lowered bearings (I find cone and plain bezrings cannot be driven by small belt, for it requires but small amount of load to stop it). For the belt I use an ordinary belt lace cut in copper wire hook. n Its life is about two years of Difterent lengths of belt are required for differentof u daily jobs. have one long piece and a few pieces various lengths. ut is useless (hooks causing a jar) and there is no other means of readily joinng. ; Fig. 3, it will be noticed, is a group of details. 182 The Model Engineer and Electrician. A Colonial Reader’s Models. By H. WeitzEL (New South Wales). August 25, 1904. from a piece of brass of square section; a small hole is drilled at each end, at right angles to one another; two aes of brass are then lightly riveted on one end and en to boom (see rawing), a piece of wire being then inserted in the other end, N Fig. 1 is given a scale drawing of a model sading boat. The dimensions of the boat are Length on deck, 27 ins. ; length on L.W.L., and bent so as to form a staple, which staple is on L.W.L. is pointed at both ends. The hull is at bottom of boat as shown, there being astopat one end to prevent fin from sliding too far back. Alump are finished } in. thick, the deck is } in. thick, fore fin is made to slide out for convenience of carrying. here is no running rigging to raise or lower the cut from a sold block of cedar, sides and bottom aPaER into mast. The fin is made to slide in a slot of leadis cast on bottom of fin, of shape shown. The Defail of fin Fic. 1.—Deratts or Mr. H. WEItzEL’s MopEL Saitinc Boat. and aft of skylight, andis strengthened at intervals by beams put across the boat. The sky built up separately of }-in. stuff, on a pase of 3-in. the baseextends } in. forward of mast and } in. at back of skylight; the ends are cut to take }-in. deck at ends, fastened with small copper tacks. The deck runs right through to outer edge of hull, and a. half-round bead planted on top (see drawing); the base of skylight is reduced to } in. at outer edge-so as to showsameas the rest of deck. The port-holes are made as shown; a slot i chiselled inside of hull and a piece of glass put in, and slot puttied up again. The gooseneck is made (Scale : 4th full size.) sails, everything being fastened with hooks, I formerly used running rigging, but found it more trouble than use. Sails can id taken down without any trouble when hooks are used. The boat sails very fast,‘considesing her size, one man in a dinghy having his work cut out to keep in touch with it in a good Fig. 2 shows a model electric enti, drawn to : scale, dimensions of which are as follows :— Length on deck,, 26} ins. ; length on L.W.L., 25} a is pointed at both : ends. The hull is cut from a solid:block of cedar, Septembet 1, 1664. The Model Engineer and Electrician. 202 A hole was hes drilled in the base at the place the compass is to take a 4 in. roundmarked by asher was next placed beheaded brass screw. how impossible it is to give any hard and fast rule for computing the position of this centre; and the on the top, an insulated wire, with a loop at one end, being placed between the top washer and the arm, and a screw put through and driven eee into the be based on actual experience. tween the brass arm onalthe base, and a similar one hole in the base. Lastly, two escutchcon pins were e tension a the screw driven in to act as stops. thatholds the arm should ie regulated so that it slides fairly koe over the contacts, but, at the kes good contact with the screw-heads. relative positions of the centres of lateral resistance and that of the sails must, to a very large extent, When calculating the centre of lateral acai the rudder, if always carried, must, of course, be included inthe plane. The actual effective draught of any surface is the lines A B, and it will be seen shownin Fig. 4 how the total area decreases with increased angle of heel, and hence the greater the stability of the tight, as is the case in the one I have described. Model Yacht Architecture. By W. H. Witson THEOBALD, M.A. Waler /evel (Continued from page 162.) I,—LATERAL RESISTANCE. ATERAL resistance is the resistance offered by the water to the hull, by which the latter is revented from making leeway by reason of the pressure of the wind on the sails. For calculations the under water body of the hull be a flat surface, as shown in Fig. 3. is assume This, of course, is not theoretically correct, as the tion) presents a curved surface to the water, but it is sufficiently accurate for the pur Lee of finding the centre of lateral resistance and balancing it with the centre of effort of the sails. This centre of lateral resistance is the point on the under water body at which it would be possible to move the boat sideways through uae 7 without either the bow or stern twis centre of lateral resistance, so found expanimentally in a bath, is the tvue centre for the boat in an upright position; whereas the centre found by treating e under waterx body as a plane surface would be a tana out, but not sufficient to make a Then a; difference in the calculations. re fact that the model is not sailing in an upright keel entirely alters any position so found L Fie. 4. model, the more effective will be the lateral plane better resistance than disturbed, and so a lateral plane with light draught and much ich the shallow bodied boats, with deep dagger-shaped centre boards, worked their way to windwar $ therefore, it is always advisable to ue as much eer edge as is possible. reference to Fig. 5 it will be seen that in A the eating edge extends from a to b, and the water, CLR therefore, flowing along the rectangle from ab to oi.cb is twice as great as cd in Fig. 5 A; 580, Fic, 3. The rounded sides of a boat offer very little actual f leeway, and hence the be to gi n angle with the horizontal pressure of the water when the boat is heeled. Further, when the model is moving at any speed, a wave is thrown up on the lee bow, which will tend to alter the position of the original centre, throwing it forward. All these conditions show assuming that the sections of the boats, the under water bodies of a- re a by A and B, are the same ; then adeb ia paca be a flat surface. Hence thie “ehidiaice & uld probably be twice that of A, ew cn acti areas of the two planes are the sam The objection to the triangular profile, as shown in B, in a modelis the fact that the ae keel would ngle and the The Model Engineer and Electrician. September 1, 1904. simpler nor more efficient than the triangular form of plate. Under a racing rule in which draught of water is untaxed the lead can be kept low, and plenty of lateral resistance obtained by use of the deep fin, ee there is a limitto the draught of water absolutely necessary, which is governed by the amount of stability needed. Asbefore aac, it is the cutting edge which does the majority of the work, and hence the double fin, as fitted to many models under the old rule was very successful. The water, disturbed by the first fin, had an opportunity of settling down again before coming into contact with the vertical edge of the second. Under the present rule, however, the draught is taxed at ‘6 of the L.W.L. from the fore edge by the 4d element, and it is necessary to avoid any useless draught at that point. The lateral resistance can best Be obtained by giving a considerable rake to the keel but not to such an extent as-to jeopardise the sail carrying capacity, due to soll righting moment in con- sequence of a high-pitched centre of gravity of the lead As regards the position of the centre of lateral resistance. In modern boats it is usually found to be about 1-10th of the L.W.L. aft of the centre of c = b a and damaging the propellers that at one time the boat looked as though she would not be able to run in the race at all. The third prize was won by Mr. David Scott’s Bonaccord, which for three lengths of the lake gave a splendid exhibition of speed, but fouling a piece of string on the lake Sap: the last run down, chance of winning the cup was completely lost; if the last run had ao all right, hewould have undoubtedly done the 590 yardsin 2 ies and 50 sees., including turnings. n his re-running his heat over again, he unfor- tunately ran on the side of the bank and sostrained his first run “clearly Sco ts the steamer members that in his boat they had undoubtedly a most formidable rival for fhe challenge cup. Mr. Scott Keay, and he repeatedly did the 100 yards in the b on Central Fic. 5. the L.W.L. and ‘or to ‘03 of the L.W.L. aft of the of the sails. This position will vary with the CE the ordinary deep fin type of under water body, boat requiring the centre of effort of the sails to be further forward of the C.L.R. en a boat with a triangle profile. As an average, ‘02 may be taken. ON Thursday, July 28th,this Club held one of its well attended SS ae races, which . B. Birch’s Three w. resultedin a popular lake (590 Sisters, which did the Guar lengths of the marvellously yards), including turnings, below aad present fastest time now Park lake for that distance. The time worked out gives a speed of 84 “miles an hour, a marvellous performance. The steamer members of the Club thoroughly concerning speed, as his boat is quite a different type of model from those which the Wirral members are accustomed to, both as regards the boilers and the way in which she is driven, and the result of the (To be continued.) The Wirral Model Yacht Club. hel y Mr, time in ee eg in 3 mins. 7 secs. r’s Era secured second ae Mr. W. her time forthe =60 yards being 3 mins. 50s eared ihe third whilst Mr. Kirkpatrick’s Doris and 4 s her time being 4 mins. Club held ‘another On Saturday, July 3oth, the for the Commodore’s oa steamer (Roy M. must be absolute boat running high | dry on the bank and so twisting the shafts as well as he was able under the circumstances, gave a private exhibition of speed on the lake, he being very kindly assisted in this operation by the three Mr. Tharmes, and Messrs. Weaver and a — : present new ow On the Monday raoueae following this, Mr. Scott having repaired the boat A. dk did the 590 yards in 3 mins. 17} secs. intends coming down next year, when he is fully determined to lift the cup and take it back with him to Scotland, and nobody wouldaoe to see this x Mr. W. R. Weaver, the a “| 203 It was won by Mr. W. a Weaver’s Eva, which race, and this was Laird, N.A.) handsome silver cup, which won three times before it can become the property of any member of the Club. visit will certainly lead to a further increase in the speed of the Wirral steamers, besides creating the keenest rivalry between the Club and Mr. Scott in the coming MoDEL ENGINEER Steamer Speed Contest, and the members one and all hope Mr. Scott in that contest will have more luck with his boat than he n that competition than their fellow Club member in far away Scotland. 4; RODUCE PyropHoric ALLoys for igniting gases, Welsbach, in his French patent, uses one or more of the rare earth Ag eeepc ees cerium, &c.—fused together withiron, 30 per cent. of the latter giving the best resiiltasioe or cobalt may, however, be used instead of theiron. Suchan alloy, when rubbed with a file, emits brilliant sparks, i are capable of igniting a mixture of air and The Model Engineer and Electrician. 224 appear to be the case from a casual inspection of the exterior of the engine. This course should only be followed in models which are provided with the same-sized firebox as the prototype. If there is any extension of the latter forwards beyond the coupled axle then the tube plate should be placed in the usual position directly over the back covers of the cylinders. The original engine has Joy’s valve gear, with the valves on top of the cylinders. Whilst the design of cylinders adopted in the 7 E. locomotive may be gear used on the original employed, the Joy’s valve scale cannot be very faithfully ifodelled under Iawould of about 1 in. to the foot, and even then not altogether recommend it owing to the number of joints it entails—all of which must be more or less of scale dimensions. Should any model locomotive builder who cannot lay curves of sufficiently large radius for a | September 8, 1904. Model Yachting Correspondence. | | | Three Model Yachts. To THE EpitTor oF The Model Engineer. Dear Sir,—I herewith enclose a photograph and description of a group of model yachts made and sailed by myself, as a member of the Hastings and St. Leonards Model Yacht Club The model yacht in photograph a right hand 1o-in. beam, os 1,000 sq. Sheis four years old and has done a lot of sale about The central one is Dan Leno, only just finished. Sheis a skimming dish, 36 ins. over all, 13} in beam, 2} ins. depth of hull, with a centre-board 10 ins. deep which fits in a centre-board case andis can be a bolt on deck, and held in position with taken out for convenience when being carried. She Mr. ALBERT GRANT’S THREE MODEL YACHTS. .Y.R. engine of the No. 1400 class, modelled closely to scale in its main dimensions, still wish to adopt this engine as the prototype, and at the same to the ‘scale’ time does not Jane. eeeneenG actice, he may pro- ceed by ioeune the total ates! base, by not only f cutting down driving wheel diameter and coupled the stroke of the cylinders and length of connectme-rod may be reduced (as in the engine No. 271, n the Great Northern), and the cylinders pushed focwend from under okebox, as shown in sm Fig. 24, This illustration dep icts in outline an o very much like, in its main features, the Y.R. y be made a scale Pea of 22 ins. ae thereabouts, in place of 26 i To be continued.) has a lead bulb of 6} Ibs. Her sail plan is a Clyde lug, measuring 1,242 Sq. ins., and jib with 460 sq. ins. very oot in a breeze, but has not yet She is r been sailed in any She is made on the sandwich principle brs, thicknesses), viz., 1}-in. and 1-in. planks of whitewood, and is put together with white lead and screwed; Ma only weighed, without her centre-board, 44 lb The boat on the left hand is te Shamrock, ns ins. of hull, with fin over all, 9 in. beam, 4} in. depth keel, which is fitted and has a bulb of lead weigh- She also has not been raced yet. last two boats, viz., Dan Leno and Shamrock, have both been built in spare time. The Shamrock’s sail plan is: Mainsail, 936 ins. ; jib, 420 ins. ing 6} lbs. sail, 276 ins. She also can set a spinnaker with 67 ins., making a total sail area of 2, 299 sq. ins., and when running before the wind with a heavy and all Omi set she leaden rudder of 14 lbs. weight truly. travels very fast.—Yours St. Leonards-on-Sea. ALBERT GRANT. September 15, todd. © The Model Engineer and Electrician. Model Yacht Architecture. By W. H. Witson THEOBALD, M.A. (Continued from page 203.) a guide to the reeitis abn a various wins, the following table has — compiled :— Velocity III.—Sait CarryInG Capacity. RLEF mention was made of the aie moment of the hull as compared with the sail trying capacity of model in the first avian of this s-ries (page 160). If a hull, when 245 hull, and this result again by the pressure of the in lbs. per sq. in. on the sails. as ur. | ae | per sq. in. in miles | Pressure in Ibs. ‘ ee za 4/5 | Light 6/9 12/13 17/18 | Mod 1ate Fresh Strong | 001 003 ‘007 ‘O14 The sail area found by the equation of the moments is fore, if the eee moment of the hull at any angle is known and the pressure of wind in per sq. in. is also assumed, then the theoretical area of the sails in sq. ins. can at once be calculated to give the same moment to the sails as that acting on the hull, the equation being : the resultant area presented at right angles to the pressure of the wind. SAxPxH=ean in which S A = sail area in sq. i P= pressure of eneon sails in lbs. per sq. in. H = height ihe E of sails is above C.L.R. of hull i L = length of righting leverin ins. DuIM = displacementin lbs. From which— For the purposes of this caleulation, the wind is assumed to be acting on the sails as if they were a A _ Wind R Fic. 7. Fig. 6 shows a model heeled to 20degs. A Bis one edge of the sail, and C is the centre of effort. Now, it is clear that the wind is not acting at right angles to the surface of the sail. To obtain an equivalent to A Bat right angles, a line must be drawn through B parallel to the water level or to the direction of the wind, as at B D, and A D drawn at right angles to BD. AD Now a cosine DAB = cosine of angle of heel = cosine 20 degs. Theis AD we cosin: angle of heel. or, in other words, if the area found by the formula of moments is +, the actual area that can be put the boat is Fic. 6. flat surface at right angles to the direction of the wind, and the windis assumed to be acting through the centre of effort of the sails, a point which bears the same relation to the sails as the C.L.R. does to x cosine angle of heel. Again, in computing the moments of the sail, the height of the centre of effort above centre of lateral resistance was used, C to E, in Fig. 6. For the same reason as before, CE= P ins.) that the centre of effortis above the C.L.R CF cos. FCE~ CF cos DAB And so the sail area can be further increased by The Model Engineer and Eiectrician. 450 the cosine of the angle of heel; or, as a general sail, ifx is the area calculated from – moments, then the fees area to be a mayb (cos. aie of heel)*. a model should be able to sail within 45 degs: of the ind. ann Fig. 7, let AB be the direction of the wind; then a model, to reach the point A (starting from B), should first take a course as at BC, and afterwards along CA. The line BC then will mebtesers the fore and aft line of the t. For such a course the sails should be set at an angle of about 11-12 degs. with the line BC; therefore the angle at which the wind will strike the sails will be equal to (45~ee tas = 35 degs. ,let BA seer strength of the wind, andB the direction and the angle of the sail with the wind; the naa represented by AB can be resolved into two forrces, one represented by C A acting at right angles to the sail, and the other by BC acting parallel to the surface of the sail; this latter force, so far as propelling and heeling power is concerned, may be neglected, and there September 14, 1604. is felt ; and further, a model can be pressed down with greater safety than a real yacht. A further 10-15 per cent. might be added over and above the area found from the two main factors. Assuming an angle,of 33 degs. for factor 2, and an inclination o degs. for factor 1, and 10-15 per cent. added, the sail area found by the formula SA x H x =LxD may be multiplied by 2°25 to 2°5 to give the actual area which the model is likely to be able to carry. (To be continued.) A Model Rotary Converter. By G. E. RADE EREWITH are t of model rotary converter Iam just Eatin and which has taken me about eight months to build. I started work on the field-magnets, which I had cast in malleable iron at the Leys Malleable Iron Casting Co. These field-magnets are two castings, and after drilling them and bolting aa together, I bored the tunnel out to 1 9-16ths diameter. This I was obliged to do on a friends le as I do not possess one myself. The fieldnets I insulated with paper and shellac, the bobhin ends I cut out of cardboard, and after baking risk of these breaking off. I had pea opera building a dynamo, “but just before startingw on the armature a friend suggested that I ald soldered to piece! make it into a rotary converter instead of a dynamo, and so get alternating current as well as direct current. I saw it would be very little more work to put slip rings on the pulley side of the armature, and that it would bea lot more interesting to have alternating current and direct current to experiment with, so I determined to build it as a rotary converter. I therefore made the shaft longer to allow for four slip rings to go on. The armature stampings I bought from Messrs. Whitneys’; they have eight slots and are 1} ins. diameter. ‘These I eae on the shaft and he uae up with a nut, a lo only remains the force shown by C A, which represents the actual wind pressure on the sail. Now aa sine of ABC; ABC x BA. And so, if 1xfee the force of the real wind in therefore CA = sine of nut also beingu commutator, ack i think was the ae difficult to build, I made out of SI m these eight holes I tapped 4in. I het cut out two diameter. pieces of blac e 1 in. diam- Ibs. per sq. in., then the actual force acting on the ABC. sails is equal to x x sine of angle Summing up :— The sail area found by the moments of hull and sail can be increased by dividing it by the cosine of angle of heel square 2. The wind pressure can be “decreased by multi- plying by the sine of the difference between angle— of course aepela angle of sail with fore and These are “We two main factors by which — approximate sail area can be increased; but, matter of fact, the area the model can actually aft line o is due carry will be found to be even greater. This not flat surfaces, and to the fact that the sails are the wind is spilled off them before the full pressure = diameter. I drilled a the centre of this, and eight“holes see equalAa this (4-in. hole): eter and drilled aes correspond- in the brass. ing to the holes I Tapbed ¥4 tat made a mark over each holein the ov Fic. 3. brass and a similar mark i th eight pieces with a saw, making the brass into I had, therefore, eight cuts between the holes; shape shown in Fig. 3. These pieces of brass, the jeces were then screwed between the two piezes of fibre, ane seeing by the marks where each piece I got a very nearly round commutator; had to go the space cut amy by the saw I] filled up with 1 then drilled a }-in. hole in the centre of each mica and shella The Modei Engineer and Eiectrician. 280 A Model Sailing Yacht. By Wm. B. Hart. 2). were rete ‘through HE principal dimensions of this model are :— 1 treme length, 33 ins. draught, 7 ins.; L.W.L., 24 ins.; sail area, ,100 sq. “tas, The hul fourteen thicknesses of brown paper glued over a_ solid Mr. W. B. wooden ; mould after September 32, i904. brass wire was driven on upwards from outside, in a similar manner to a barrel Oo and hoops (see Fig. ht ED means of a . ave a flange which fits the outside of the boat soldered to them ; another wooden flange was placed on from inside the boat and held in place by hard wood keys, Hart’s MopEL SAILING YACHT. thoroughly drying it was painted, and rubbed Sheet rubber was used to make the joints water— {see Fig. 3). € projection of the a through the hullis held ae against a bulkhead. Two wooden blocks are secured to the bulkhead, the fin comming between not bent, but cat 4 them, a pin holding all together (see Fig. and } in. thick in the centre. The deck was fitted inside the hull, and an endless band of half-round being to have a frame, as it were, consisting of the 1} ins. thick ; as finished, it is } in. thick at the ends The deck is screwed to the poles (of which there are two—one for each fin), the idea aimed at September 22, 1904. The Modei Engineer and Electrician. deck, bulkheads, fins and bulb keel, the paper hull merely keeping the water out, so that should, by pe chance, the hull get sodden, no strains should rown on it. or this reason—stiffness—the bulb keelis of gunmetal, in two halves. The spars are of yellow pine, except topsail yard, whichis hickory, and wereall cleft togeta straight grain ; all the spars are ferruled, and were given two coats of varnish, The rigging is spliced, no knots being used. The sails are made i were cut and hemmed on a Wheeler and Wilson machine by myself, the hemming being done under 281 the withdrawal of the carbonic acid. It has been ound, however, that the phenomenonis not due to this cause, but to the establishment of conditionsin m, containing mere traces of impurity, is left in contact with dry gases (oxygen, carbon dioxide, mixtures of oxygen and carbon dioxide), rusting does not take place. In the presence of the same gases and water vapour no rusting — so long asa cyeagaee! a aa (34° in the actu if the temperature is allowed| ie fluctuate, viguid za Deck~ Fic, 1. Za Deck METHOD OF FIXING THE Deck. Fic. 4. —-ARRAN GEMENT OF HOLDING FIn IN THE Hut. Wooden keys [eee poles flange vasher G2 SSS SES == QS SS Brass flange Fic. 3.—SIDE VIEW AND SECTION THROUGH FIN. DETAILS OF MR. very strict domestic supervision. wards sewn round the edge W. B. HART’S MODEL SAILING YACHT. Cord was af ter- water condenses on the surface of the iron and rust is produced. It is thus shown that pure iron is not oxidised in presence a oe end put in its place to ous he boat has been sailed, and I mae she far exweet my expectations in every respect. The Rising)of Iron. R. DUNSTAN a ults ae a an h summary of unfinished in- quiry into the reactions invcived in the rust- i i While both liquid water and oxygen are necesary for the formation of rust, the —, of carbonic acid is not er although it may accelerate the action. The well-known effect of alkalies and alkaline salts in Weevertints oxidation of iron has been_hitherto attributed to nitrogen which ha oxygen was employed, rusting did not occur, but if oxygen or a mixture of aaa and carbon dioxide From these results, was used oxidation took place. it is evident that for the formation of rust oth oxygen and liquid water are required. experiments in which a mixt carbon dioxide was used, indicated that in this case a secondary action pro- ceeds simultaneously.—Pvroc.” Chem. ea 29, 1904. _. The. Model} Enelneer. and. Electrician. Model Yacht Architecture. meee multiplied by a constant, which is usually written as 7, and may be taken as equal to 3°14. If the radius of the circleis oe the area is, of course, radius squared multiplied by +. The ar i of a semicircle or quadrant will be obvious (Fig. By W. H. Sucox“Tabobarn’ M.A. iaialaaies from ‘page 250) Four-sided figures bounded by. straight Pines: _ IV -—CaAL CULATION oF Seessines Square or rectangle. “out” headsails, ‘‘in” ‘The areas of these figures is the product of any two adjacent sides (see Fig. 11). HE plane surfaces met’ with in model yacht architecture may be classified as follows :— Trian, aes such as 297 Circle.—The area of a‘circle is half the diameter Parallelogram.—Product of any side and a per- and pendicular a from may Civeles sich, as lead bulbs. wedge: © (Fig. 1 that side to the side Trapezium. a Pcatiaat of the shortest of the two Four-sided figures bounded by straight lines, such as mainsails and Jackyard topsails. parallel sides and perpendicular from it to longer side + product of same perdendicular and half the A A A pb Cc BC Area=4 x ADxBC DB Area=% xADxCB FIG. 9a. such as the water ius aie in the half- breadth Fic. 10, (Fig. ae ab four-sided figure, such as a mainsail.— O The simplest method of finding this area is to divide the figure into two triangles byjoining two opposite angles and finding the area of each triangle separately; afterwards adding these areas together. Three-sided figures with one side a pied curve.— : By asimple curve is meant one such as shown.in Fig. In yacht eu aiicoiane this curve is ueualy an BA A wm FIG. ge. ie ca. between lengths of the two parallel sides a > Area £xACxCB Fic. 9b. Three-sided figures, two sides of which are straight “Mines and the third side a simple curve. Three-sided figures, two sides of which are straight lines at right angles, and the third a line with either convex or concave curve, or both combined, such as the half sections of the body plan Two-sided ee ae of one side a straight ws line-and the other a curve, convex, contave, or bot B Reclanq/e. Sguare. Area=AC xCD Area=ACxCD or AC2 Area 48 xT or(B cham Methods for computing these areas will be taken in turn, Triangles.—The area of a triangle is found by dropping a ee a from any angle to the Fie. D C 11. arc of a os ora adie pags one the area of the be thus found: Me BC and calculate figure may the area of the triangle ABC;ihengae the length of the longestPel sa peenes which can be drawn meet thecurve, and the area of the from BC. to opposite side, or this side cae ie and multiplying this poapentinthy by the side on which it figure CDB E-is 4 of the perpendicular D E multi- the two sides eomlainine the right angle (Fig. 9). curve and two-sided figures with one side an irregular falls, and dividing the result by 2. If the triangle contains a right angle no coe ee need be drawn, the area being one-half of the product of plied by chord CB. The area of the figure ACE D is then the area of triangle + area of figure C D BE. Three-sided figures with one side an irregular The Medel Engineer and Electrician. 298 curve.—These figures are mostly found in the bod plan and half-breadth water-line plan of the design; and for calculating their areas two rules are in general use: (1) Simpson’s rule; (2) the trapezoidal rule. The latter is the simplest, but is not so accurate as the first. Therefore for calculations which require to be exact Simpson’s rule should always be used; but the second may be depended on if the plane is long as compared with its aie and if the curved side is not abrupt in any part. The lower water lines, for instance, of a keel boat may be treated by this second rule, but the lead keel should be calculated by Sim Sig s. Simpson’s Rule.—For the purposes of using this rule one of the straight sides must be divided into September 29, 1904. would ae a —-2A in. each, and this we will assume be t the The diivisions on AB should be numbere a 1, ., Starting from either end, and the petperidicutae drawn to meet ve. the ae w for the rule. Add a ata peee of all fhe perpendiculars numbe oe nd multiply by 4. Add together all -_ iinet “odd,” excepting the first and last. and multiply by 2. Add together the first and last, and multiply by 1. Total up these three results and multiply by 4 of the distance the pee eka are apart. The resultis the area of the pla o make a compact table of the working it is usual not to actually take out the “even” and Fic. 15a. A eT 70 9 8 7 6 6 4 3 2 f Fic. 1-6. Fic, 15c. Parallelogram Area= ABxAE Trapezium. Area =ABxAD+ADxCD D C an equal number of even divisions, and these divisions are numbered 1, 2, 3, &c., starting from either end. A convenient number of divisions is ten, but 15 (a), To illustrate the working a this ao rFig line from circumstances may require ane a section of a fin boat. ivi i In(a) the length AB parts, each of which will be assumed to be 2 ins. long. Therefore, the total length of A B is 20 coe In (b) the section is suppos: been drawn, an a ry already- eyfrom AB is 6 ins. eithies have been Now, ifin the design the loweris water already conveniently drawn 1 in, apart, the section In (c)the fin boat, the length from BC would probably be inconveniently small for division, and it is usual, therefore, to draw the _perpendiculars to an equal number of parts. Suppose, for instance, A B were found to be 2} ins. long, then four divisions D Fic. 13. “odd” lengths and multiply themey. but to work them in one column pe be taken as an example first of a ‘ 3 << ditto. #0 as 19 . T1053) 4 5 6 277 3°05 3°45 8 9 10 3°4 2°85 1°85 7 iI Fig. 15 (a) will To = eal Lengt er pendicular. tiplied by. I 4 ee 10°8 61 138 4 2 4 13°6 5°7 74 rt fe} I Oo fe) 2 4 2 3°55 Result. . 42 3°8 2 | Fic. 12. a or AD (AB+CD) D 5 C Total oe 72 Total to be multiplied by 4 of the distance the paprika 7. meen In this case the distance is 2ins. Ther ae *33 Sq. ins., which is the eery dis figur The Model Engineer and Electrician, September .29, t904. Fig (b) will be worked out in the other way, us :— o. of per- pendicular. 1 Lengel a8 A Design for a Model Compound Undertype Engine and Boiler. 5 2 3 By HENRY GREENLY. 4°5 3°55 (Continued from page 556, Vol. IX.) 2°32 4 1°375 6 *95 7 299 ° Those numbered ‘“‘ even ”’ viz., 2, 4, and 6 added together equal 7:77. This multiplied by 4 gives 31°08 Those numbered “ odd ” excepting the first and ; last—viz., 3 and 5, added together equal 4°925 and this multiplied by 2 gives 9°85. s A MaxinG Pump VALVE-SEATS. N continuing the description of the details of the undertype design, a coloured plate of which was given with the issue of January 1st, 1903, the next most important portion of the work is the ump. After careful consideration, the diameter of the ram has been fixed at # in. Theoretically, with a stroke of 7-16ths in. the amount of water forced into the boiler at 400 revolutions per minute should be nearly 20 cubic ins. per minu owever, at such a speed the efficiency would not be more than 50 per cent, ; therefore, 10 cubic ins. per minute is the utmost that can be expected. At this speed (400 revolutions per minute) the engine would be consuming about 6} cubic ins. per minute; therefore, if the efficiency is considerably less than 50 per cent., the pump should be sufficiently large to meet all the demands of the engine. To prevent a ‘* flooding ’’ of the boiler during working, the pump has been fitted with a bye-pass cock, by means of which any excess of water may be returned to the tank, and the feed regulated to the requirements of the engine. The pump body consists of a casting in gunmetal affixed to the facing on the side of the bedplate The first and last equal (5 + 0) x 1 gives 5. The three added together equal 45°93, and this multi plied by 4 of the spacing, which is in this case Iin., gives the area thus— 45°93 X } X I = 15°31 sq. ins. The last figure (c) will be— No.ofperp. Length. Multiplier. I ° I °625 2 °875 3 10 4 i 5 5 Result. ° 4 25 4 42 2 I 75 Ils Total 6 g°6 is to be multiplied by 4 of $, the latter being the length between the perpendiculars ; therefore, WY, 96 + 3 = 32 = 2 sq. ins. which is the area. CROSS-SECTION OF PuMP FOR UNDERTYPE ENGINE. doubled. This rule is the most important one used in yacht architecture, and should be practised by the student until he can, with perfect safety, omit column 3 is memory to carry him altogether, trusting t irst and last multiplied by 1, evens by through. , odds by 3. Total to be multiplied by 4 the distance of the spacing. (To be continued.) (see page 137, issue of February 5th, 1903). Three lugs for the screws attaching the casting are provided, and a fourth fixing consisting of a stud driven into the back of the pump body and fitted with nut and a splayed washer on the inside of the bedplate. To bore the casting, the best method would be to attach it to angle plate on the faceplate. There should be little difficulty in the matter of setting September 29, 1964. The Modei Eitgineer and Electrician. the front end of the body of the pump, through the delivery box, and just stopping short of the other side of the Sekig a ate entrance to this hole should be tapped f bib cock, and, vertically at the other end, hole should be drilled and tapped On the coloured pints THe bib cock is of the ordi- to take the deliver nary pattern, and a pipe would have to be sweated teeergg noses e y (Mrs.) E. —ilustration herewith is of a little yacht have been brought out,* Th designed and made ee beyond my power. My husband had to come to the rescue, which he did very willingly, and Iventure to say herewith. Bate te exception of the keel, which cu out iereek copper with lead ballast, this isBane Mrs. E. Bates’ Moper Satine Yacur. on to its nose; but since designing the engine, bib union 30: A Lady Model Maker. applies to cylinder cocks. For the suction a piece of pipe should be screwed he was rather proud of the result of unassisted work upto that stage. deed I have asked h a present you with a photograph of this little boat, i the underside of this valve-box and the lower end fexibi rubber pipe may be attached to connect eing put in the lathe and grooved, so that e€ pump to the water tank. (To be continued.) * See Bassett-Lowke’s catalogue. a piece of i total depth of 5 ins. I have @ okpetietice in the havin making of a yacht beyond that of seeing different patterned boats on a dam, where my husband and his friends sail their models. An océasional visit The Model Engineer and Electrician. 402 there gave me the idea that I could design and make a yacht. That I have accomplished it to the satisfaction and the ieee iat ee those who have I aouliey a small space in aut ae journal. some who en her sai was asked for the loan of my patterns by fancied her shape, but as I Aen destroyed September 29, 1904. A Small Planing Machine. y S. B. anno J. "THE little machine which we are about to deSs said to our- selvés, ‘Itis going to bea sift ee:iui we thought arrived, and water-line) quite eas- when we saw pee scribed for the holes, which were drilled -in, tapping size and tappcd Whitworth, being The ‘‘Gauge’’ Competition. Wishing to encourage model makers to let us and their fellow-readers see what they have accomagain offer to send a ’” lumbus should be accompanied by the title of the article and stating exactly what n other d. potltes of the sender on hoto- the graphs andany separate sketches eve with the aren should similarly bear the name arise ii the awarding of the prizes. It is essential in this, as in our other competitions, that the copy- right of the photographs must be the property of the senders and the covering feu should contain a declaration to this effect. New ELectric ae—A new type of lamp It resembles the has’ been invented in America. of a metallic ordinary arc lamp, but a- leclioiesThe positive ds.. Fic. 1.—A SMALL PLANING MACHINE. fixed a the bed by $-in. set screws, one ineach foot. then filed and scraped We the V’s on bed and cardia: the adiastian strip was drilled with dients, _ this is slowly consum PossIBILITIES OF PEAT Gas.—Some experiments e in. German three 4-in. holes and fixed to carriage with per sunk screws, the carriage having two }-in. set x of same, which makes the caaiiage a good sliding fit, without any shake. The rack was then taken in hand, being filed out at centre, leaving a shoulder at each end, this shoulder taking the strain of the cut, the rack being fixed to the e of Z-in. bright s teel 114 ins. been a difficulty, the results are of importance. as the long, and turne deen to $ at one end to go through the bed. Qn this.end the pinion is fixed with a The Model Engineer and Electrician. October 13, 1904. Model Yacht Architecture. 348 No. on * Length 5 (0). Perp. I By W. H. Witson THEOBALD, M.A. 5 2 Halieag of # lengths of perps. 45 4 2°32 Totalsum oflengths of perps. 5 1°375 VA fo) 3 IV.—CaLcuLATION OF AREAS. (Continued from page 299.) The Trapezoidal Rule.—The simplicity of this rule lies in the fact that the straight side may be divided into any number of equal parts; thus, in many instances, the re-division of any lengthis dispensed with. Further, there is no multiplication of odd and even perpendiculars. The rule is as follows :—Take half the length of the first and last perpendiculars and add to the total lengths of all the 3°55 6 °O5 1 and 2to6 inclusive = 12°695. spac a 2°5 = 15°195- Spac: I in. therefore 15° ies x line = "195 sq. ins Difference from Simpson’s rule is 115, or? % Fic. 15 (c). No. of Length. Perp. I . 3 2s 2 others, then mnultiply by the distance of the spacing. fo} 625 875 5 ls 4 B 105 Halfbooe of lengths of perps. Tand 5 = °575. Totalof lengths ofEpetps: 2 to ;, ineluswe = chavs isen in 5 = 2°55. 3°125. Therefore 3°125 xfin=r 953. Difference from Simpson’s rule is-047, or 2°35 %. V.—CALCULATION OF CENTRES. D Having found the areas of the different figures, it will next be necessary to calculate their centres. The centre of any a a simplest mode of procedure, this method will be first explained, afterwards passing on to the theoretical treatment. The centre of any plane is the point at which it is possible to balance this plane horizontally on the point of a pin or needle. The figure is cut out of stiff cardboard, or very thin wood, and balanced on a needle-point until it rests horizontally ; where the needle meets the surface of the plane is the centre of the figure. Another method is by suspension. Suppose it is required to find the centre of lateral resistance of the surface in Fig. 16 (a), which represents the under water sheer Fic. 16c¢. Illustrations taken in turn: of A, B, and C, in Fig. 15, will be oint Don the cardboard, take off the pi ape draw a line through hole A and pencil mark a Fic. 15 (a). No. of Perp. Length. a?) 2 1°05 4 27 5 3°05 6 3°45 7 8 9 3°55 3°4 2°85 3 ro 19 1°85 Halfsum of lengths of perps. Nos. 1 and 11 = Totalsum of length of perps. os. 2 to 10 inclusive = 23°80 2338 +0 = 23'8. Spacing is 2 ins. Therefore 23°8 x 2 any 47°6, which is area figure in square sneha, = of The difference between this calculation and that Fic. 16a. ° found by Simpson’s ruleis +73sq. in., orabout 14 %. The centre must be somewhere in this line. Nase suspend the figure from the hole at B and dra 346 October 13, 1904. The Model Engineer and Electrician. another line B E, Fig. 15(c), the intersection of the two lines is the centre of the figure. Asa further check the plane may be again suspended from the third hole at C; but if the lines B E and A D have been care- fully ‘drawn, and the figure swings easily, two lines point on the line GF, at which the tae centres a ps The rule is as follows (see Fig. 1 Let A =tse of pe centre G. ,a= of figure CE BD centr y = length of ite Spee centres centre. (vi.bn G B) = distance from G will be sufficient for ordinary calculations. This method of finding the centre is of most use in the case of the centre of lateral resistance of the under water bod Triangle.—The centre of a triangle is found by dividing any two of the sides and drawing diagonals from the points of intersection to the opposite _ angles; itionthe diagonals intersect is the centre to resultant By fhe law ofleurs: | forces— (y - *) of the triangle. Another method is by drawing only one diagonal, then the centre is 4 of the diagonal from the base (Fig. 17 (a)). e centre of a square or rectangle is the point of Then G H is drawn equal to x and H is the resultant centre. Therefore, the distance the resultant centre of any two centres A and a the centre A is ual to the distance the two centres are apart ( all probability it will have been drawn with a pair centres instead of areas, the result would be the same if instead of A and a, W and w (the weights in lbs.) had been used. This equation should be remem- tiitemeerton of diagonals drawn from opposite angles (Fig. 17 (b) and ( centre of circle ae eeaige be given, as in of compasses and the aceuis mark will have left an impression on the pa A multiplied om ae oee the other (a) divided by In cquation (r). tad sarclghite been placed at the e sum of t “ B E FC= $CD, EC=3EA BF=AF BE=ED Fic. . 170. D method of the centre mony! figuresis by meansbot triangles. to use it in of are shownin Fig. 15 (a), (b) and(c), are found by a continuation of Simpson’s rule. eferring again to these figures (a) will be first taken Thecolumns as they stand are again set out, and the last results in column i should be drawn from opposite angles dividing the Fig. Find the centre of the triangle A BC and mark it as at a; then the centre of the triangle BC D, figure into four triangles, as in s and, lastly, the centre of the triangle D A B at d. Join d band ca and the point of intersection is the centre of the complete figure. ext figure is that shown in Fig. 19. Join the ends of straight lines to form the triangle A BC. and so on until 11 is multiplied by 1o. The results at these eee are placed in column 6: the total sum of which is then divided by the total sum of the products a column 4, and the quotient multiplied by the distance of the spacing. is oe fo s: the longést perpendicular possible is drawn from C B to the arc CEB; from D measure off along DE two-fifths of the pe Sen and this point F is figur the the centre of t is now necessary to find the resultant of the Join the two centres by means of the line GF; it is required, therefore, to findsome distance the centre is from perpendicular No. 1, and is measured off along the li Ciladation of CB for Fig. 15 (a) :— No. two centres. frequently necessary e centres of all other irregular figures, such as 17a. finding is relation to the weights of different parts of fis boats. Four-sided figure bounded by straight lines.pr easiest Fig. 17¢. bered, as it L. Multiplier. Results. ° I 105 4 A'2 I 3 19 2 3°8 2 76 4 § 6 7 8 9 27 3°05 3°45 3°55 34 2°85 4 2 4 2 4 2 10°8 61 13°8 71 13°6 57 74 3 4 5 6 7 8 9 32°4 24°4 69 42°6 95°2 45°6 66°6 I ° 10 ° II 1°85 ° 4 Total = 72°5 ° Results. I 2 10 ° Multiplier. ° 4°2 Total = 387°6 346 October 13, 1904. The Model Engineer and Electrician. another line B E, Fig. 15(c), the intersection of the two lines is the centre of the figure. Asa further check the plane may be again suspended from the third hole at C; but if the lines B E and A D have been care- fully ‘drawn, and the figure swings easily, two lines point on the line GF, at which the two centres balance. The rule is as follows (see Fig. 19) :— Let A = area of triangle centre ,a=a f figure BD ce * : = length of line ageg centres (vi.by GOB) = distance from G will be sufficient for ordinary calculations. This method of finding the centre is of most use in the case of the centre of lateral resistance of the under water bo: Triangle.—The centre of a triangle is found by dividing any two of the sides and drawing diagonals from the points of intersection to the opposite _ angles; wiles |the diagonals intersect is the centre to resultant centre. By the law ofjeer, forces— x (y—#) (A 4a) =ay Xr) ey of the triangle. Another method is by drawing only one diagonal, then the centre is 4 of the diagonal from the base (Fig. 17 (a)). The centre of a square or ee is oe alee of intersection of diagonals dra fro opposite angles (Fig. 17 (b) and ( Then G H is drawn equal to x and H is the resultant centre. Therefore, the distance the resultant centre of any two centres A and a the centre A is ual to the distance the two centres are apart (y) all probability it will have been drawn with a pair of compasses and the pose mark will have left an impression on the pa centres instead of areas, the result would be the same if instead of A and a, W and w (the weights in lbs.) had been used. This equation should be remem- centre of circle ee eg 8 be given, as in A multiplied om the area of the other (a) divided by In auation, (1) had weights been placed at the e sum ofthe two areas a“ B BF=AF BE=ED E FC= $CD, EC=3EA Fic. D 17a. Four-sided figure bounded by straight lines.—The easiest method of finding the centre of these i irregular figuresis by means of triangles. should be drawn from opposite angles dividing the . 170. Fig. 17¢. bered, as it is frequently necessary to use it in relation to the weights of different a of the boats. e centres of all other irregular figures, such as are shownin Fig. 15 (a), (b) and (c), are found by a continuation of Simpson’s rule. eferring again to these figures (a) will be first taken Thecolumns as they stand are again set out, and the last results in column perpendicular, thus 1 is multiplied by o, 2 is multi- i and so on until 11 is multiplied by ro. The results a these anne are placed in column 6: the total S and, lastly, the centre of the triangle D A B at d. Join d band ca and the point of intersection is the centre of the complete figure. The next figure is that shown in Fig. 19. Join the ends of straight lines to form the triangle AB - Now, if the area containedin the curved line C E and the straight line C B is very small, this area f perpendicular possible is drawn from C B to meet the arc CEB; from asure off along DE two-fifths of the PE eenas and this point F is the centre of the figur t is now necessary to find the resultant of the two centres. Join the two centres by means of the line GF; it is required, therefore, to findsome sum of which is then divided by the total sum “of the predicts in column 4, and the quotient multiplied by the distance of the spacing. No. is measured off along the li Cilbsiation of CB for Fig. 15 (a) :— No. L. I ° I 2 1°05 4 42 I 3 19 2 3°8 2 76 4 27 4 10°38 3 32°4 5 6 7 8 9 10 II 3°05 3°45 3°55 34 2:85 1°85 ° Multiplier. Results. ° Multiplier. ° te) 42 2 4 2 4 2 61 13°8 71 13°6 67 74 9 66°6 I ° 10 ° 4 Total = 72°5 4 5 6 7 8 Results. 24°4 69 42°6 95°2 45°6 Total = 387°6 The Model Engineer and Electrician. October-13, 1904. is marked off at G (see Fig. 15 and This method as applied in Fig. y 5 (a) only oe the position of the centre along the base line. In most instances this is sufficient, as the figure will the actual centre of figure (a) is required, it will be necessary to divide it equally by lines parallel to, by using the then, ase line A B an the lengths of these parallel lines instead of the perpendiculars in thesecond column, and working in be found, and this is then set up from the centre G first found along the base line. In figure (b) as the perpendiculars are drawn at right angles to the line A B, the distance found for the centre will be measured downwards from A along A B, and this will be the centre of the whole section below the Calculation of centre for (b) in Fig. 15 :— No. I 2 8 4 5 6 7 Length. 5 Multiplier. I 45 4 3°55 2 4 2°32 2 1°375 ° 4 "95 1 Result. 5 Multiplier. fo) 1 18 2 vant 9°28 Total = 45°93 pie body, viz., the displacement, in cubic inches, s found in the same way as were the areas of the different figures in Fig. 15, using again areas instead of lengths. Calculation of centre of buoyancy and displace- og ah oad water line of the boat is divided a number be sections oe (for connto &c., starting from the venience)nanenberell & ore en The area of cael, section must be calcu- re according to the manner shown in either b or of Fig. 15. The area of either half, or the whole, ces ee may be used in the table, but make a rule f using one or the other and sticking to it. It will then be practically impossible to make the mistake of calculating twice or half the displacement, It will be assumed that half the areas are to be used, These areas are then placed in column 2 of the table, and are multiplied by Simpson’s multipliers, A Result. ° 14°2 3 5 19 6 fo} the second colum: And instead. 18 27°84 4 2°75 38 347 AB Therefore, the centre is 10°7 ins. pie A along 11 to) . Total = 90°04 Therefore, as the spacirig is 1 in. this is the centre of the distance below A the full section below water, of which A BC is one half. In(c) Fig. 15 the age will be found This e AB. somewhere along t ealeulalion, a is really an unnecessary-section o the centre of half a If the centre boat is not wanted.required, the is D the tiated are parallel tion must be divided so that the usual course followed. below the L.W.L. to the L.W.L. (A B), and For approximate calculations, however, of a fairly flat bottom boat, the curve may be assumed to : Fic. Cc 18. viz., even sections by 4,odd by 2, first and last by 1. Totalled up, and multiplied by } of the distance the sections are apart. The last result gives the contents in cubic inches of half of the under water body, which multiplied by 2, will be the contents of the whole under water body, or the cubic inches. i Now, there are 27°65 cubic ins. in 1 lb. of fresh water: so if the contents in cubic inches is divided by 27°65 the quotient will be the displacement of the model in i buoyancy is found e position of the centre of 4 the table. The results in column =bt of the are multiplied by a less than they number the other section (exactly in the same centres were found) and the results are placed in column 6. The total of column 6 is divided by the total iin column 4 and the anpkisay is multiplied by the distance the sections oe apart ; this, then, will B be a parabola, in which case the centre may be taken as 2-sths of the depth B C measured down- wards from So far, all the calculations have been confined to areas: but the most important centre is the centre of buoyancy, which is that of a solid. Happily the give the distance the measured along the L.W.a is aft of section No, 1 But anes it is required to know the distance Well, then the disthe C.B. is below the lacement may be calculated from the areas of the half breadth water lines. This will can a enecke on the figures for the displacement as w As a matter of fact, however, it re “common 348 The Model Engineer and Electrician. practice to not so accurately calculate the posifion of the centre of buoyancy below the L.W.L., but A Steam Travelling Crane. By sia NELson, d for a design (which will be ‘given later) both the the section plans will be worked, and it will be then seen how much one differs from October 13, 1904. N making this model I decided from the outset to use only such Sees asI aay possessed, h other the m ss The fore and aft position is, of course, most im- go various motions keeps the is made to The engine operator no scale, n ve &c., whereas there cutting, no scale drawings, and not a pattern casting, except ake nor buy a id , and facilitate the fixing of the wicks, and a glass gauge to show the height of the One handle starts, stops, or means of a reverses the engines by two-way cock which is fixed at the top left-hand side of pened (Fig. 2) an looks like a square bloc spirit. The cylindrical Cal in front of is an exhaust box, cock the two-way the exhaust steam passing out at the top and up the chimney, while the con- Fic. 1.—EnpD VIEW oF MopDEL STEAM TRAVELLING CRANE. portant, as it gives a rule for placing the lead keel, the centre of gravity of which should fall almost directly beneath the centre of buoyancy of the hull, (To be continued.) the arrangements or working the slide- valves instead of using eccentrics. There is, of course, a spring to keep the slide-valve pressing against the cylinder face; without this s on the crankshaft is a small pinion which gears into The Model Engineer and Electrician. October 20, 1904. (2) Preferably gas. youwill need an engine of 3 p.h.-p. at least. hunt wound, 100 volts 18 or 20 amps. (2.¢., ae Co) leads are necessary. (6) Ordinary”wood casing, unless the place is 381 dynamo, with armature 1} in. diameter and have wound it similar in ig. 49, MopEL ENGINEER se I ane. 10, with the exception that only eight slots eight segments wound at an angle of sligh tly less than 90°, asand ineere are two es damp ; the wireman would settle this. 12,593] Model Yacht Architecture. oO. (Gateshead ) eee (1) What can be learned from a Tnowiedge of the‘‘ centre of effort’ of a sail plan? (2) How is the“‘ centre of buoyancy ( how much sail is needed before the mast to balance that which is abaft the mast? (4) Has a Clyde. {ne sail a gaff, or is the pointed top of the sail attached: ito the) (1) T orked out so as to hav: a ae ot its aefelative to thesbent re of lateral resists of the hull. Theoretically, these and all cores and shaft ; I should b blig asouth; carbon pasnes ee he ees full width ofone seg- ments -_ by a wire as per Fi ment, an an angle of 90° ; two brushes, and the o posite se - We very much doubt if you will get such a machine ito be selfexcitiing. Af pol es The armature anou 1d be wound with about oO gauge wae to. give any prospect ofsieee and copper brushes must be s is extensiv!ely ilson-Theo! a Yacht Architecture,” b . He ., now running in THe Moper "ENGINEER. (3) Thisis quite optional. For a model about 70 per cent. of the is the use of 14-in. hole shown in same ». drawing ? s f winding preicrable to ordinary winding for ranmees nar re58 to (1) ver:he coils are wound into correct formin place on the (2) The coils are to be sprung into diametrically 1,000 w: block. opposite The angle of the winding n the case is different, in machines up to 1,000 watts omeuat least, it need only be e adopted as a matter of interest on the part of the maker. [12,501] Wire Reslscances, &e., (ormesby, R.S.O.) and Gauges Vv. writes:Would you kindly let me know (2) Winai length of No. 30 copper wire will give a resistance of fhull. (4) H Feoe ae Ne. 30 B.W.G.? (2): I suppose I.W.G. and BW. are length of it would give 1 ohm resistance? A CLypE Lue SAIL. If you would aban a table it gauges of wire and relative resistances I should be total sail area should be abaft the mast. There is no question of balance as regards the sails themselves. The balance really means balance between centre of effort of all the sails and centre of lateral ist 1 ohm ? ow is electrical wire numbered—I mean is the abov. e No. 30 -W.G. or Query N° 12593. a éketch ofa Clade l i gla very (1) Five yards L.S.G. copper has a Eianee f (2) Imperial tel Standard wirewiregauge a foe om [12,640] Dynamo Output: Volt and Ammeter. (3) No. 34 L. (4) One ohm wouldrequii ‘77 yards (see January rst, 1901 issue for a table of wire Bauer west eices, etc. )s ]12,352] Draughtemans| hip. E. -K. (Bir. writes:7 I venture to ask wl ether you could ies me(Birmingham) ofany engineering 1 felis am, who employastaff of drau; ghtsmen as I am leaving school, and would like to entera a drawing office. ones as you think possible as I think I could manage the delicate work required for t 8 c.-p. ro-volt lamps very readily, id w advise you to use either 5 c.-p. or p. lamps, or some of each ; 8 c.-p. lamps are not usually made for less than 15 olta. If you can get the you mention, ys ch is 1 to an opening 3 lamps; you ae rockon exactly with Saath Yamps. A good voltmeter and ai T are/descri ibed in THe Mop for April 1st,p02, the dessign b witchboard type. For 12vvolts the additional wire mentionediia par agraph No. 4 on page 149,left-hand column, will probably not be required. The ampere me ee should be wound with No. 12 gauge p.c.c. wire— 2,645] "Fawewels Dynamo: Failure to Excite. W. ia Piero Tydfil) writes: I have constructed a small arene You should gain some ex- classes. [12,443] Installing oaall Lighting Plant. In the reply to this 70 watts, vi in their drawing office. perience in mechanical drawing first, however, at some evening seers 4 I on 2 page 239 “* 50 volts and ro amps.” should read “ 50 volts, amps. (12,513]$-in. Sparks Coil Failure. A. E. C. (Dalston) WHS & have endeavou }-in. spark co’ book. I have all bobbins wound andamounted on primacy, aad. wh to construct I have had the secondary ii n series with one spark co’oil, and fint an get a very good crue porous Deus eing teas ‘3 a os t. I have supplied drawing eauite certain about secondai ary wind- left and left to right alternately. ave wound bobbin fro: t ee Yetober 27, 1904. The Model Engineer and Electrician. ‘upper port to the lower edge of the lower port. is will give you the exact over all length to make valve, which, although shown on the drawing, ierally requires some modification in actual ictice owing to the aienly oe getting the | | mders to work exactly to dimen 399 difficulty. The glands and neck rings should be quite slack on the rods. A lubricating oil box should be fitted to the cylinder with small brass oil drip pipes to the main bearings, connecting-rod brasses, and guides. Bedplate.—This should be carefully‘lined off, put Model Yacht Architecture. By W. H. Witson THEOBALD, M.A. V.—CALCULATION OF CENTRES. (Continued from page 348.) Centre of lateral Resistance.—It has already been remarked that the t way for calculating this centre is by means of the suspension from a It may, however, a necessary to fi the plane as well ; used, which case Simpson’s rule is is scams necessary to go all through another example. T lengths of the perpendiculars from the L.W.L. to the underside of keel are placed in the first column aoe are multiplied by Simpson’s TROL EMG. the total of the results are ~multiplicd ~ 4 of the the di — the perpendiculars are apa This will give the area of the lateral plane Toelow water) in square inches. The C.L.R. is rule, found as in by the. continuation the other cases. of no For the aap purpose of ea aeRing the moment of the sails, it is necessary to know the depth this C.L.R. is below the L.W.L., and this aa be approximately found as follows :— re C.L.R.is assumed to be at a distance below the ..W.L. equal to half the mean draught. To centre of shaft OF. itaneht is the quotient of the area, found by Simpson’s rule, divided by the length of the L.W.L., and half of this mean draught is taken as the depth the C.L.R. lies below the suspension method, of course, gives the position without any further calculation Centre of Gravity of the whole Mass.—It is almost impossible to calculate this centre exactly from the drawings; there being such a great differencein the L.R. under the present rule, the displacement might be anything from 20-30 Ibs., and the hull alone might weigh 4-6 lbs., the spars ae sails 2--3 lbs., and the Se peg in the lead ke As an sons, a boatof 27 lbs. displace- cea will be taken—hull, 5 ane spars, sails, &c., 24 Ibs. ; and lead keel, 19} lbs. ee20 shows the ae of such a boat. Draw a base line AB at a convenient depth below ‘the lead keel. C is the highest point of the bow. Fia. 14.—-ELEVATION AND Seantowat PLAN i OF YLINDER, athe faceplate and the tops of the bearing recesses ad. bosses for columns faced S$; the sarees teesses should be either filed or planed o nd ae brasses should be carefullyfitted and fen,pated at with a boring bar while in place, great care es taken that the fore and aft centre lines of parings and cylinder coincide. Such parts as jlinder covers, eccentric ae glands, &c., are | \ raightforward pieces of work presenting no nd foundto fall at Thisis the centre of gravity of the hull, at which 5 lbs. will be ae The centre of gravity of the lead keel may. be taken as } in. below It will fall a little above the centre owing to there October 27, 1904. The Model Engineer and Electrician. 4co being a greater mass of lead at the top end than at thelower. At this point 19} lbs. are acting. The centre of gravity of the sails and spars may be assumed as acting through the C of effort of the sails; the boat would carry, say, 1,600 sq. ins. and this centre would be roughly speaking,, about AB. A table is then 34 ins. above the base line made thus : t and centre pl the hull. Having found th of buoyancy of the model therefore, and assuming a certain weight for hull and gear, a portion of keel 3: is cut off to represent the lead keel and its contents in cubic inches calculated by Simpson’s rule. are 2°44 cubic ins. to I There Multiplied by Result Hei dl 34125 36 Total = 155°125 Total = 27 The total of the third column is then divided by the total weight, and the quotient is the distance the resultant centre of gravity is above the base line. 155°125 27 = §°745 in. {edious of any during the design of a model, it being one of “ trial and error’? the whole way through. Unfortunately for the patience of the draughtsman, it is also one of the most important as regards the amount of accuracy required, so must be per- allow for Always required. This distance is measured off and is the centre of gravity of the whole mass. ec D—— does not fall exactly where required. tion for position and size of keel is, perhaps, the most whereas, if found to be too light, a new keel will require to be cast or else inside ballast used, 1 Ib. of lead on the keel is worth considerably more than Rz |bs Sails.—The position of this column the lengths from the base line are tabulated, and the rest of the working is precisely the same. In drawing the perpendicular for the base line it is most convenient to have all the centres lying on the base line from which the measurements are to be made. d some on the other, i K¥ 3765 _ +Cenlre of whole mass. height above the L.W.L. should be found by using this L.W.L. as the base line. The actual area of each sail must be taken, and not the area of the fore triangle as measured by the Y.R.A. rule. ; TURBINE (To be continued.) STEAMER’S SPEED RECORD.— We understand that the Midland d Railway turbine steamer Vickers, Sons A Base /ine Fic, 20. The weight of lead on the keel ot a model yacht usually bears a larger proportion to the whole displacement than in the case of a real yacht, and for the position of this lead it is usual to place its centre of gravity directly below the centre of buoyancy of Com- i 3 the measured mile she gave a speed Hitherto steam pressure for turbines has been kept q. in., but in this vessel 200 not only to higher speed but to economic results. The Manxman has been built for Heysham and Isle of Man service, but can be used on the Belfast trade. She will carry 1,500 passengers. 448 November 16, 1904. The Model Engineer and Electrician. Model Yacht Architecture. By W. H. Witson THEOBALD, M.A. (Continued from page 400.) VI.—CurRVE OF STABILITY AND METACENTRE. HERE remain now alculations which are usual in yacht architecture, but which are not absolutely necessary, although of great interest to those who wish to go thoroughly mee the subject. A curve of stability simply eans a curve which will show at a glance the Unb ae moment ”’ of the hull at any angle of position for the measurement of the } G and 4d > elements of the rule Now, the centre of buoyancy is very seldom found so far aft as section 7, nor yet so far forward as section 6, which is the centre = the L.W.L between these is situated generally about midway sections, and for the purpose of calculating the stability it will be better to take off another section at the exact porate = the centre of buoyancy for n the other hand, if its fore and aft pos L.W.L. had been A eventig divided in the first the instance, say, into twelve equal parts and num- bered 1, 2, &ec., from the fore end; it would probably be found’ that section number 8 would be sufficiently near to the centre of buoyancy to justify the curve of this section being used be rememmust It that bered the calcula- ancy is found to fall is drawn off on both sides of Fig. 21. iJ Fic, 22, heel, To work out this curve in all its exactness which is a most tedious operation; but a plan gives very oer accurate results may safely be used The ue of the method is to find how far for model wo e unnecessary to calculate at less than every ten greesof inclination. The first step will be to find tie position of the centre of gravity of the whole mass, which will always act through the same point no matter what the angle of heel, and will also act downwards at right angles to the water level. Having found this centre of gravity, it is next necessary to know the position of the centre of buoyancy for the fore and aft length of the L.W.L. (see issue of October 13th, 1904). It is usual to divide the L.W.L. at thecommencement of the design into ten equal parts and number the sections 1, 2, 3, &c., starting from the fore end. This is the more usual now that the rating of racing pas has two of the elements measured at ‘6 ofthe L.W.L. aft of the fore end, and the section Let 7 will be the exact the centre line, thus aan uaa the complete body The centre of gravit at may be taken as that of a 42 L.R. of 11°5 ins. beam The area of the section, as shown, is 36 sq. ins., Lc would give a displacement of about 26 lbs, Allowing 1} lbs. for the a 4o ft. water line. weigh of the Dart &c., acting Ar point 20 ins, above the W.L., 4 lbs. fo: for the lead keel, the centre of gravity of the whole mass will be found at 3°8 ins. below the base line is taken at the leyeeEeee of the lead keel Vi coe_petow the water line t Length above ae tiie, Moments, 27 = 40°5 x Tr (sais, &c.) a 4 26 5.95 = 22″ 2 x (hull) i x 20°5 (lead) 83°2 : 26 = 3°2 ins. == 20°5 83°2 The Mode Engineer aid Electrician. November 10, 1904. That is, the centre of gravity of the whole mass is 3°2 ins. above the base tne, or.7 — 3°2 ins, below the L.W.L , which equals 3°8 i Therefore, 26 Ibs will Be acting downward through the point G, 3°8 ins. below tthe L.W.L. s the twohalves ane identical, only half the area a the Sentiadl need be calculated (if convenient), and the result afterwards doubled. e equal CD Fo eal hence it follows, since the length A C is always constant, and in this case equal to 1, that the denominator for the sine y angle to a radius 1 is always unity, and the nanwe ater is equal to the length of the perpendicular drawn from the end of the revolving radius to meet the base line BA. If then it is desired to draw a line to make any particular angle e with the line B A, the table of sines is referred to this sine of this angleis °174 ; therefore, it is known that . ow draw a line rants E at 10° inclination. Perhaps the student has no protractor or a table for finding how to draw this line at the proper H nN ‘ expressed by the fraction AG? The first angle required is one “et 10° and the e submerged original section, viz., 36 s “ado On reference to Fig. 22, the circle is drawn, with a radiius of1 in. The’ sine of the angle BAC is circle been made 5 ins. long, the equation would still have been r©e—_ ‘174, from which the perpendicular C D would have been “174 x 2 (since AC = 2). : Having found this length, draw the line = 0 V\R BA=’174 ting the circle at C, and join then the angle contained between C A and BA will be one of 10°. Having drawn this line on the section as H E J in Fig. 21, the D next step is to calculate the é of th area as the original: section, viz., 36 sq. ins. In most cases it = be found to be J too gre The _ethod for finding x the area section | is and @ me of the nes from the ‘out’ wedges. tn 21 the the area contained figure C E J F is common to both seeGNE, First find the area of the “in” wedge (HCE) by means of the triangle HCE and the small figure outside the line H C; and afterwards the area of ‘‘ out ” wedge. In ‘the figure, these areas are 2°84 and2°53 sq. ins., respectively. 4 inclination, aud, therefore, it may be convenient to give a simple method for doiing so, he following table gives the value of the sines and cosines of various angles to a radius of 1 Angle in degrees. Sine of sadlets toradius1 Cosine ° 10 20 re) ud a “174 -. -» “94 *866 The new line, ray Sa a be drawn * 766 “866 *766 zis we «s we °643 “OS below H J asat LM. “94 es oe 2342 zs oe *643 50 _ 60 a ae 70 a I This can be done by Theline H J, which is 10°4 ins. long, mami by a certain depth ¥ must be equal to °31 sq. — “5 ave a area equal to *31 sq. in. an equation as follows :— From which— .. 342 re ee 90 “in’’ wedge is added to the a a 30 40 80… The eriginal area 36, making 23° 84 sq. ins., ane the out ” wedge then deducted, leaving 36°31 sq. ins. as the area of the whole of the inelined. section. °985 ae — °985 = °I74 O * = oq = The ‘03 ‘03 in. two areas are now of equal size and the gene of buoyancy of the inclined section must be fou e best way to do this is by Simpson’s rate, i is di equally into an ev m perpendiculars aie 43 meet the curve of the ‘ 450 The Model Engineer and Electrician. section. The procedure is ee exactly the same as oe et in this si The working is shown inihe following table for the jaulinacion fe) No, I (The Edttor tnvttes readers to make use of thts column for the full TABLE, Multi Lengths. pliers. fe) Results. pliers. 1°94 4 31 4 12°4 6 4°7 4 8 6°5 2 18°8 13°4 4 6 26° 7 9 2°7 2 3 2°56 5 2 3°68 g. 10 II 5°12 2 OF 1°5 fe) 7°36 574 4 I To 102°24 fe) 7°76 a@tscussion of Bates of practical and mutual interest. Multi- I 4 2 November 10, 1904. Practical Letters from our Readers. 2 A Design for a Powerful Model Locomotive. 10°24 3 To THE Epitor or The Model Engineer. 37°2 4 DEAR S1R,—By wi way of a friendly criticism a 29°44 5 Letters @ nom-de-plume ty desired. mas the full name and address of the sender must invariably bi though not necessarily 4ntended for publica ior 1.) fe) 7°76 94°0 . SC 80°4 182 8 — ed with Results. fe) I 43°2 9 10 54 tal = i 24 Trraloar 24 multiplied by }4 of the spacing, in this case 1/08,’ will give the area, and so checks the result of the previous calculation for the area. ‘There is almost boundto be a small error. The second total divided by the first and multiplied by the spacing gives the distance the centre of buoyancy of the inclined section is from 1 (in this case 5°26 ins.), and is marked off along LM at B’. Now LM is the new water level and it is known that the pressures through the centres of buoyancy and gravity act at right angles to the surface; therefore, the of the hullis for 10° inclination, 26 multiplied by scene for each 10° degrees of heel, as one drawing apt to get seed confused with the number of teal lines draw. t an inclination of 30° and more the new water level will, in all probability, fall over the rail as shown in Fig. 23. This will give a little more troublein computing the area and centre of buoyancy for the inclined position, but one illustration will show a way of surmounting preference to a ode which shall for its weight and the amount of the work expended upon tt prove as powerful as possible in actual working—is not, in SY forces represented b O which, is *75 in. The displacement being 26 lbs., the “ righting moment ” Jonge of —_ “inch lbs,” that is, 26 x *75= 19°5 Ibs. tt will be safer for the beginner to draw a new Fic. 2—WIDTH oF GRATE FOR SOLID FuEL. Without laying stress on the fact that the design—unless the Deora |builder has in mind only a model o up-to-date ”’ locomotive, in ARE centre of buoyancy must be somewhere along a line N B’O drawn through B’ at right angles to LM the weight of the displacement must always act through G at right angles to LM. The length of the righting leveris the distance between the two and the difficulty. The same section will be taken as in Fig. 21, but for an inclination of 40° (see Fig. 23). is drawn at an angle of 40° with line H J i 5 The line CED. Con- fair line to meet Deg of the and ‘out’ wedges as before; using the triangles E and HCE, and also the small extra pieces cotained outside the lines J D and C Now the edge is too large by the figure H R Q, which is mn part of the boat, so calculate the area of this excess, and deduct from the first area of the “in” wedge. Having now the actual areas of the “ i ue and “out ’’ wedges, proceed as in the previous case, using the line R J as the base, find how much below this line the new level L M must be struck so as to deduct the eo ons make the area LM KCQ equal to 36 sq. i (To be cont eel ) 1 Fic. 3.—SECTION OF FIREBOX ARRANGED FOR OIL FuEL. my opinion, the best that could be put forward, as a smaller type of locomotive to a larger scale would not only be more efficient, but could be made to pass around sharper curves. I would like to point out one or two features detrimental to the perfect success of such a model. The chief one is att the firebox. | | Supposing that solid fuel is to be © sed; the grate, owing to the relatively large driving re will be, in a } scale model very shallowin- | 474 The Model Engineer and Electrician. Practical Letters from our meaders. November 17, 1904, the port quarter. The part A BC is hauled tight by the boom sheet and tiller, therefore pulled up to indward—z.e., starboar ded. part dacenel off by the same amount as A BC ADCis has been {The Editor invites readers to make use of this clume for the full may be signed with a nom-de-plume name and address of the sender MUST uetably be attached, though not necessarily intended for publicat: Steering Gear for Model ‘Yachts. To THE Epitor oF The Model Engineer. Dear Sir,—I a am sending you herewith a part plan sketch show wing the steering arrangement which I have endeavoured to fit to my model sailing yacht, and which is taken from THE MopEL ENGINEER for July — 1904. I cannot work it, either theoretically or in practice, aus neue be glad of any if your readers could hel The main-mast is situated 9 ins. +n”the rudder stem. The description is as follows :—The main sheet is rove through two quarter blocks and hooked to the tiller and arranged so that the harder the main boom is set over by the wind, the more the tiller is pulled thereby up to windwar The leverage of the tiller can be adjusted to suit the wind by shifting the sheet hooks. The way I take it is this : Supposing the wind blows the boom over bows, the connection A BC he opposite direction, which is most simple and obvious. But.on the other side the connection ADC is being drawn up equally as much as the other connection A BC, so that when A reaches a certain point in a straight line drawn from the mast to D, the connection between A and D has obviously reached its shortest length, if it gets even as far as that; so that if it was required that the boom should be set still gnere to leeward, the connection A D would have to be drawn out elongated, which is, of.course, stout as ABC is pulling the rest of it in the opposite METHOD oF WoRKING le GEAR FOR MopeEL Yacu tightened up. In the article, the triangular part of the sheet is drawn flat for illustration purposes ; but in practice it leads up to a holein the boom, just above the tiller end.—Yours faithfully, ndon S. J. THompson. The Metric System. To THE Epitor or The Model Engineer. Dear Sir,—I am pleased to see that in THE Mopet ENGINEER for November 3rd you have made the introduction of the metric system the subject of a leading aiticle. Ir pressing this hee the attention of your readers you are, in a public service to the English. . This is a subject which should be studied by everybody, and your remarks reaching as they will in due coirse young engineers—both amateur and professional—in all parts of the world, cannot fail to helpin the solution of this question. I have read the pamphlet referred to in your article with ae and recommend otheis to do the PLAN OF STEERING C (3 out that much mation is to be found in the Journal of the Institution of Electrical Engineers of London, No. t60 of Vol. XXXII, Part II, issued GEAR, in March 1903, under the heading of “ Notes on the Metrical System of Weights and Measures,” by Alexander Siemens, oe and the dis. pape direction. Anyhow, I had the whole thing working experimentally (full size), with temporary boomand tiller, and it quite failed. I am afraid I must be awfully dense, or else I have made some mistake.— Yours truly, Croydon P. G. MANSFIELD. To THE Epitor or The Model Engineer. DeEaR SIR ,—Referring to your correspondent’s letter let the wind be assumed on the starboard side, when the main boom will be pulled over to both sides, and it is, perhaps, hardly fair to select examples from one side on y, but since = remark that ‘‘ the flow of public opinion seems o have been eo in the direction of favouring the proposed change,”’ whilst giving figures to show November 24, 1904. 489 The Model Engineer and Electrician. Model Yacht_ Architecture. By W. H. Witson— M.A. ive of a “inch Ibs.” The length of AC should B—and as A convenient length—say, half as long should be divided to represent a trifle more than the greatest number of inch lbs. in the hull moments. VI.—CuRVE oF STABILITY AND METACENTRE. (Continued from page 450.) HE me of the centre of buoyancy needs more y small, excess LS Q (Fig. 23)ise Tice . Iffoes L Be grommet and the line an appreciable size, the ites”of ths: figur If ofinto two equal parts the line Q L may be “divided T perpendicular at T, and a line drawn through to SL, meeting this line at V and the curveS Qc at W. Then use V Mas the base line, and acs the centre of uayanty of the figureV M K CW the usual way. — 50° 60° O° 80° 90° 30° to be 19°5 in. Fterelore, at the division along hting m AB marked 10° measure upward until opposite the markon AC, which represents 19°5 in. lbs., and mark this point. in. lbs. ° the moment is 41° 6 tion whichis known, afterwards drawingin the curve through the points marked on the perpendiculars, The line A B can be sub-divided into any number of parts; 5° is chosen as a useful spacing for a model, as minute angles of heel are not what shows 20° sta- 70° hat oo — the stability increases rapidly, ee maximum when at 65° inclination; and even at 90° she would quickly recover as soon as the pressure of the wind ceased. It has been shown that when the righting Fic. 24. same strength. as AmotLBe diagram of the same kind, which shown in Fig. 26, may be drawn This will a sufficiently accurate results, if the is carefully done; or, again, the “ give- and-ta sectionmay ei cut out of cardboard, and vee centre of Lea | found by the suspension method. the section with all te. inclined .Fig. 24 shows O, water jites drawn, and the respective leverstoG the GO’, &c., set off from the centre of gravity , &c., drawn through the perpendiculars NO, new centres of buoyancy. 10° angle of heel will give a different Each ag to tan by length for the righting arm, which is give the various lbs.), to 26 (the displacement in equal spaces, each space and divided into eh“C eee is drawn at right angles to thus, Fig. 2 to represent 5° AB, and divided into equal divisions to represent will show exactly where these moments will balance with different pressures of wind. The curve of stability is again plotted in, but the per- f a smaller scale, and Firstly, a lbs. to thesq. in. will be taken, equal to a light breeze. receding chapter it was shown that sail n area decreased as (cosine)? of the angle of heel. i i Now, i altering, so instead, the wind pressure will be taken as decreasing. This makes no difference whatA boat such as is now 24 ins. above the centre of lateral resistance. the (cosine)? of various angles will be; used fre- quently, a tableis given for reference. The Model Engineer and Electrician. 490 Angl fe) TABLE OF (COSINES).? « 10 46’1 for 20° 97 884 30 40 50 60 75 “587 diagram, and then a curve is drawn in through the points. This curve represents the “ sail moment” at any angle of inclination for a wind pressure of “117 80 03 fore) ‘002 Ibs, per sq. in. The point at which the curve of hull , _Tighting moments ’’ and the “ sail moments’’ cross one another is the position of hull, Pie) It was further shown that the sail area aight be at which the forces balance; and if a perpendicular increased by dividing by the sine of 33°, due to the angle formed by the wind striking the ‘sail. To is drawn from this point of intersection to the base line it will show exactly how far the boat will be heeled : in this case just over simplify the figures, the sine of this | angle will be as ae ‘6, and, therefore, which may be The mom “1650 X ‘OOI2 X 24 X (cosine 20°)”, which is 42 in. lbs. ; and this is set off on the 20° “413 25 70 November 24, 1904, This is set oft on the ee drawn from AB at the 10° mark. (Cosine).? I 20 taken in. Ibs. any particular wind or a stronger wind pressure it is only necessary chosen can be multiplied, firstly, b A light breeze of *oo2 Ibs. pressure per sq. to alter P in the equation— SA x P x L = Moment. 400% 380 360 340 320 300! Q 280 B 70° 20° 30° 50° 40° 60° Angle of heel 7O° 80° 90° Fic. 26. may, ee be treated as ‘oor2 Ibs. pressure per sq. in. SA € moment of the sails is— ; as 24 ins., and the leetee the light bneeze as ‘002 lbs. per sq. in. Ww The iene of the hull is. is ‘OoI2. therefore, for the upward position 1650 X_ OO12 X 24= 47°52 righting moment of the hull for an oo oy This is roanbed offup AC, as in in. Fig.2 the position is 0, and, therefore, the sail moment will tend to heel the boat eh The “sail moment ”’ for an ae of 10° 50 X ‘OOI2 Xx an eecos, 10°)? The upper curve in Fig. 26 sey that due to a lbs. per sq. in., which for the upright position gives— strong wind of Say, ‘015 sq. m CLR (Cosine 10°)? is ‘97, and so the sail moment is 1650 X ‘OI5 X 24 X ‘6 = 356in. lbs. And for 10°— 1650 X “O15 X 24 X ‘6 X in. lbs. (cosine 10°)? = 349 Here it will _ seen that the boat would be heeled to an ang 574° beats sailing. This is rather and the model would EaPeey be given a Lae ith. suit of sails to start These curves are @ most interesting subject, and for purposes of judging unknown qualities are worth pages of figures and calculations. November 24, 1904. The Model Engineer and Electrician. VIT.—METACENTRE. 4ot 4 Breadths on L.W.L. The point of intersection of the original centre vertical line of the boat and the line drawn through the new ae of buoyancy of any inclined angle, such as Fig. 21, is calle ‘ metacentre.’ I 2 3 On UF ues to Fig. 24, it will be seen that this oe fe) 1°52 2°88 3°92 4 5 metacentre is not a fixed point for every degree of 100, < » 90 4°92 3°8 , 147°2 = 5°4 II be 102°5 60°24 «% 5°5 10 fo) 351 23°89 oe 5°28 y 8 9 C ae 4°68 6 heel, altering its position for various inclinations ; it will finally work lower and lower towards the Cubes ° 166°37 ts 157°46 . TIQ‘I 54°87 . fo) ‘Dikpiacément = — 26 lbs. N 80 26 x 27°65 = 71°89 displacement in cubic ins, 8 7) Sum of cubes = 8 60 — x 50 x 4 the spacing 3340°56 8 40 er 8 8 30 . Sob & 718°90)3340°56(4°65 287560 — <0 <70 E i AQ” 70° 20° 30" 40° 50° 60° 70° saad centre of gravity, until, in time, it will coincide with the position of this latter centre; and when this happens the “righting lever’ will be of no eagth at all, and so the ‘‘righting moment ’’ nil. Stability will. then be lost, and the boat will be unable to right herself. In a keel boat this condition would not be reached until an angle of considerably more than go° had been reached ; but in shallow light displacement boats it is quite possible for the ene to coincide with the centre of about 60°, or even 50° of heel. And the danger of the unballasted open sailing boat so frequently seen on rivers. heel—say, u — % X 4°65 = 3°1 = distance the a is above the centre of buoyancy. Fic. 25. angles of 431340 80° 90° Angle of hee/ For small aG4gee B o 20° for of pee was foundto be 2:2 ins. below the L.W.L., and from w, by the calculations from Fig. 21, the centre the distance of N above the L.W.L., by actual measurement, is, for 10° o to ‘5 ins. ; give 2°2 + equal ins.—a difference of -4' If, however, a greater angle of heel (say, 20°) iss taken from Fig. 24, the distance of N above the L.W.L. is -8 in., which would give a peel height above the centre of buoyancy of 2:2 + -8 = 3 ins., whichis approxi- mately correct with the result found by the table. keel boats, and 15° for fin—the position of the meta- follows :—The half breadth may be calculated as plan of the L.W. plane is divided into an equal number of sections, as Fig. 7 which may be taken as representing the L.W the boat, of which Fig. 21 is the mid- : aes he trapezoidal rule is then applied to tli —— of cubes, taking half of the first and last (in this case each is 0); add to the total of all the others, and multiply the sum by the spacing. Assumingthe L.W.L. to b by the displacement This product is ee in cubic ins. displacement in Ibs. is 26; an ere are 27° ee cubic ins. to each Ib. of water ; therefo 26X 27°65 = 718'9 = displacement in— ins. Two- thirds of.this quotient is the distance the meta- centre is above the is not much Fic.. 27, real object in knowing this pose of calculating the sabi for a small angle of length i . divided There metacentre height, excepting, perhaps, for the pur- n centre of buoyancy. The following table will show the method of working this length more clearly. beoyancn and gravity to have been calculated, eel. Thu and the distance of the metacentre from the centre of buoyancy to have been calculated from the halfbreadths of the L.W.L. It is required to find the length of righting arm for 10° of heel. On referring to Fig, 21, the ee which is 3°8 in C.B. to N = 2° 7 i Se es are C.G. to L.W.L., a ~W.L. = 2°2 ins.; and The line NS O hei aid through N, making an angle of 10° with NG; o that ONG = angle of heel = 10% A perpendicular is then drawn from G to N O, meeting N Gin Then OG ON = sine ONG, 492 The Model Engineer and Electrician. .OG Aefae of lever) as GM = GN x sineONG. And ye :so 0G be ae - sine ONG sin iN G = sine 10° = +174 J G = *748in., November 24, 1904. ae will continue aspo = ae current is kept |on, All these =e are due cs“the upward draught which may be taken as ‘75, the same result as the actual measurement found (Fig. 21) in the original instance. caused by the heating of the air by the discharge, and the more nearly continuous the discharge is, the greater is the upward tendency, because the air has less interval of time in which to cool. It is for this reason that the stream of oscillatory sparks produced at a primary frequency of 100 per second has a Seesaes tendency than that produced ll 3°8 + ‘8 x i OG = 4°6 X *34 at 50 per sine 20° = 1°56 ins. The first calculation gave 1°6 in., which is again sufficiently accurate. A general formula, then, is obtained for the length of the righting lever, provided the position of centres of buoyancy and gravity and the height of the singe a the centre of buoyancy are oe as fol Length of onal=helen of metacentre above centre - gravity of whole mass multiplied by sine of angle of heel, from which, by inversion, the height of metacentre above centre of gravity of whole is even possible that the ex- periment ceprbed might be yond with some degree of success with a Tesla dischar Brush Discharges.—In the course of these preliminary experiments with the Tesla coil, a phe- nomenon of a very distinctive character will probably be observed. mall tree-like, purple discharges spit off from everything metallic in connection with the secondary coil, especially from points and edges. almost peaeelly straight and exceedingly fine blue gs. lines of light, which radiate outwards as if from tho mass = length of lever divided by the sine of theangle of heel. (To be continued.) Experiments on Electric Oscillations and Waves. 38. Fic. By R. P. HowGrave-Graua\, A.L.E.E. - (Continued from page 394.) HE discharge shown in Fig. 36 was produced under exactly the same conditions as the e given in the last article, except that the frequency of the primary coil-current was 100 per second instead of 50. he sparks, therefore, took place at the rate of 200 per second. he marked difference between this discharge and the other is that this one bows or arcs upwards in a far greater degree than the other. name of arc was originally given to that familiar but ever wonderful discharge produced on drawing apart two carbon rods supplied with current at a suitable voltage. horizontal, and the phenomenon received its name because the stream of luminous gas bent or bowed itself up in curve or arc. The discharge ordinary induction coil A point where ne discharge originates. receives its name This effect of “‘ brush discharge,” by reason of the brush- jike manner in which the blue ee stick out like long and fine bristles. Large bru discharges, such as can be obtained from our com pleted Tesla coil, are imposing phenomena of very great beauty, Same and cannot be produced ease or on such a scale by any subjected in noe ee: ppevionsly described, Brush Discharge Experiments : (1) Separate “the dicchange ods to a distance of and gradually increase the primary discharge enlongh the Tesla coil until the secondary about 9 ins., connection a slight digression may perhaps be is just unable to produce a direct spark. excused for the mention of a rather pretty experiment, which may be easily performed by those possessed of a good induction coil which can be worked with a Wehnelt break or an alternating current, To each of the secondary terminals a wire is attached and bent upwards and outwards, as shown in Fig. 38. hen the current is switched on, and the distance between the wires properly adjusted, the discharge leaps across the space between them at A, and then travels upwards, in spite of the fact that by doing so it has a corresponding increase of resistance to overcome; arriving at a point where its length is such that it can no longer maintain itself, it blows out. This behaviour repeats itself, genera- trea put upon the coil than that to which it is used with a Wehnelt or other very rapid break behaves in a somewhat similar manner, and in this with the other tor of high voltage discharges. In all the following experiments with them great care and watchfulness ust be exercised at first, as there is a far greater Brush discharges of a violent and noisy character will take place at the points of the discharging rods, and will stream across the intervening space in glowing torrent, partial or complete sparks being occasionally seen as bright blue streaks, being visible in the midst of theilluminated space. This effect is inches from = ends of the rods and from the wires leading to thi Such a on is shown in Fig. 37, the scale being given only to convey an idea of the inade- quacy of a photograph of such phenomena as an accurate representation of what the eye sees, 502 The Model Engineer and Electrician. and epee of pmall gas engines to be driven from small house meter or gas b. You do ee give sufficient particulars and dimensions to enable us to give you aa aot instructions, but perhaps you can proceed ould be wound with No. 16 atur fromthe following dat: s will make as wind ; Ce gaug November 24, the date case the arate) e is not always and w: the exhau: eis bad. as q e 1904. good as it’ might be 8 [z2, ee “Model aad Building. P. H. P. (Cape Colony) writes: I should like suitable for the , further information regarding sails, &. ro rater 3 -in. ., aS contributed to THE bore of field-magnet the SSameler just Ee enough to run in the Recoils ani pole f clearance between about 1-16th in. uge S.c.c. copper wire,) getting off can olts MDs. ; less for the output you require and must be tal the new wire by weighing the old wire when et at the weights for the new wire is of much thinner gauge you will as removed, reckon same weight as before ; if y not be able about three-quarters the weight of the old wire you will be nea: of dynamo is generally known as_ th This t the mark. h.-p it. correct name for Simplex, but there is no really and how fixed ?" aro if you will Cas The and Woods, of 2, Gray’s Inn Road, London, W.C. winding should have been connected iin shunt to the armature for,electro-plating work. (Chelm' [12,772] Cells for Small Motor Boat. T. H. ford) writes: Wo uld you kindly inform me wh ere snott ‘celtuloid and are together not to be mor area for a certain enough for and another same L W beam is perhap$ too d another be: h or not om I sorry to have troubled you with my worries, but I a1 A Queer in Street ”" for the present, and hope you may find time toegive I w . in weigl > 4 i] @ “Doccoord se SiGe ” motor of the Clyhe Model internal width, hi The boatis 24 ins. ive me it quit e transparent. some idea ae -acetate? and iv i sei etbeaStgot Would these cells yewould out of them more power length of time, and Pea at of weight, than an accumulator? Could you tell me where can obtain .Photogr.‘aph or picture of H.M.S.S. Velor, or one of the hi ahdes ‘or prices, ee) of celluloid apply to one of the firms advertising oa ODEL EN material Sn T. hat es To GC Fiteh & Co., Fulwood’s Rents, poo! and fei Strand, W.C., might supply von with the photographs you {12 n| e “ao ie } Fic. 2,—-SLOTTED Botts our issue of Nov. Fic. 5.—Bowsprit. The Keel-3 thick of boltom Fig. I.—PLAN AND SECTION OF HUuLt. 17th, and also in the issue of t are to be built, and will replace certain of the cylinder compounds and light siingle- i ia engines of the‘ ‘Lady of the Lake ”’ clas bolts were fastened very tightly by two nuts and the w watertight by means of os and plenty of eA tet putty. n I gave the inside of hull two coats of white iat and proceeded to fasten the deck on, which is made of oak, + in. thick, and which is fastened on by about seventy $ in. brass screws. and the edges of deck slightly rounded. The mast socket (Fig. 6) is screwed on the deck with eight brass round-headed screws and teh 521 The Model Engineer and Electrician. December 1, 1904. bottom of socket fits tightly into a wood block screwed on bottom of hull, thus keeping it perfectly upright. The socket is turned from a piece of steel tube, and a brass collar is soldered on as 14 ins. long, and tapers from # in. to} in. Next comes the boom, which is 35 ins. long, $ in. diameter at each end, and 9-16ths in. diameter at the middle, and fits on mast as shown in Fig. 3 far down. The bowsprit (Fig. 5) comes next, and is made from ash and screws. After this, I painted and varnished the hull above the water- line black, below chocolate, and giving two the water-line gold, coats of paint, and afterwards two I only coats of best Bath varnish. mainmast is 38 ins. high from deck and 3 ins. below deck to fit into Fic. 9.—Mr. Rowranp A. Evans’ MoDEL RACING YACHT. 4 ——2/¥ | The gaff, which is 19} ins. long, tapers from 4 in. diameter at foot%to } in. at end, and it slides up and down the mast by means of a brass ring which ise screwed into socket on gaff shown in Fig. 4. A the spars, &c., were each given three coats of Mainsail 667 sg. ins Fic. 8.—Swinc RuDDER. Fic. 7.—SaiL PLAN. socket, and tapers from 1 in. diameter at bottom to 3 in. diameter at top, where there is a brass socket for topmast to fit into. The topmast is varnish, and I may say that having no lathe, I had to plane them all round and to their required size. As can be seen in Fig. 1, there is a main sheet horse fastened on deck 5 ins. from stern. e sails, which are made from special sailcloth, striped brown, bought at 1s. per yard, have a total Fic. 0.—Mr. Rowranp A. Evans’ MODEL RACING YACHT. 522 ; December 1, 1904. The Model Engineer and Electrician. igh area of 1,260 sq. ins. The mainsail is lashed stamps already sold for continuous current machines would do. But I have found that .most of these armature stamps have either too few slots, er the slots are so spaced that they do not adapt themselves for alternator work. the three other sails, as can be seen in Fig. 7, is 432 sq. ins. All the hooks, cleets, heme etc., The last thing is the any rudder, which, as The milling of the slots is, I fear, Dee’the power of niost of us.—Yours truly, G.L Canonbury, N. used in the rigging are bra shown in Fig. 8, fits on to keel by means of steel hinges fastened with + in. diameter bolts, and it is also fitted with an adjustable weight. I may say that so far, I have had the boat in the water three or four times and it sails very well indeed, going very fast. The total cost of making this yacht was 30s. interest. Some days ago, when busy at my lathe,a ain. (The Editor Invites readers to make use of thts count tor the full Uscussicn of a atters of practical and mutual R,—Permit me, for the benefit of my moral. apes ot hie brass I was turning flew into my eye, embedded itself in my eyeball. This necessifated ae— to the doctor, some troublesome Further, my pene- trated. Had this occurred, I might have lost the sight of that eye. The incident, though perha ps Readers. unusual, shows the necessity of care, and I am now jeter S ay @ pom- oeEB lume tf oa. but name and ae A Hint for Lathe Workers. doctor anes that the eyeball was nearly Practical Letters from our way be sig . To . Epitor oF The Model Engineer. it et to relate an incident with an obvious full MUST invariably he waded, though not necessarily hondelyor publication. Electricity froma Belt apology for faithfully, To THE Epitor oF The Model Engineer. DEAR S1r,—Have any of your readers observed anything similar to the Tallening, or could anyone explain the same ? trespassing on your my space.— Yours H. A. S. Ayr, N.B The Metric System To THE Ep1tor oF The Medel Eoin i Ww about 3,500 f to generate electricity accord- ing to the following experiments I have made:— 1. Standin floor and holding my hand about an inch bow the belt, streaks of pale violet sy flow from my finger ends towards the belt. Standing on a stool so as to be insulated from earth, if T hold onc finger abel 1 in. from the belt, and one finger } to } in. from the handrail, an electric spark will jump from my finger to the rail, DeEaR S1r,—With reference to my letter on the eabece of the introduction of the Metric System into the British Empire, and which you have been so good as to publishin your Journal, permit me to point out that your a ae inserted an error he name of the author of the “ Song of the Three- Foot Rule” is Hankine—a name immortal in engineering—and not “Mankin.” T shall be glad if you will kindly correct this mistake. —Yours faithfully, ‘“ WHITWORTH GaUGE.” London, E.C. giving me a decidedshoch. . Still being insulated from earth, and holding one hand close to the belt, if another person stand- ing on the floor appruaches a finger to within3 in. or so of any part of my body, a spark will pass between us, giving us both a slight shock. 4. If I try the secondAe only holding a piece of aon (suchas a hamm ead) in each hand, I can get a }-in. spark to the ‘handsai, which is adeoripanted by a slight cracklingn Ican only account for it as fictional ‘electricity, caused by the belt slipping, as it is a drive, and also the top side is the devine ae — Yours truly, Longeaton. y . P, Hand Warming Apparatus. To THE Enitor oF The Model Engineer. DEAR S1r,—The hand warmers from Japan. They are small wae in pecoratel tin, burns four hours. for small ance tesome firm See arrange to supply the required castings and stampings it would be a great boon, and I feel certain that if well designed – = would amply repay the cost oF special ttools, way out ae the stamping difficulty would be to adopt révolving armature alternators, and thus sliding lid they go into any England, they can be had in Geneva, Switzerland, from Mlle. Niederhausen (Magasin de The’), Rue de la Corraterie, at the price of 1s. 3d. for a warmer and ae rolls of charcoal.—Yours sae Cre instal- us one. or two designs and have a Being flat pocket or the feccael ofacoat. If not procurablein Alternator Design. will g: covered with velvet, which admits a cigar- shaped roll of charcoal which To THE Eprror oF The Model Engineer. DeEar SIR, a am ieEits that in ogee ments ‘‘ Zodia your correspon- dent(Query ‘No. 12,654) asks for can most likely bought at any Japanese warehouse, as they co . THoMas. To THE Epiror or The Model fea ZAR SIR,—With reference to © Query ccncerning Hand Warming Appar. s I advertised in THE few weeks _Since what the correspondent enquires about: ‘‘ Japanese Pocket Stoves.”” They are copper, i — and burn about three hours if fairly truly, sae Ford. W. H. “Hayman. December 29, 1904. Model The Model Engineer and Electrician. Yacht Architecture. By W. H. Witson THEOBALD, M.A. VIII.—Curves or DispLaceEMENT AND ‘Our’ GES, “IN” AND (Concluded from page 562.) T isnext necessary to calculate the areas of the “in” and “ out ” wedges of every section, and having done so, the net area of the submerged sections for the inclined angle may be found by adding to the area of the original section the area of the “in” wedge, and deducting from the sum the area of “out” wedge. The best method for this calculation is by a table, an example of which is given for the body plan, as shown in Fig. 28, The boat is 40 ins. on the L.W.L., and the sections Spaced 4 ins. apart : cubic ins. contained in 1 Ib. of fresh water, which is 27°65 ; and so displacement in Ibs. =487°09 + 27°65 =17°6 lbs. For finding the position of the centre of buoyancy for the longitudinal position, each of the 1esults in column 4 is multiplied by a figure one less than the centre of buoyancy is situated from section Section. Area. I fe) 2 2°08 3 Area of “Tn? Wedge. Out’? Wedge. Inclinei Secti n. ‘71 2°02 65 72 Area of 2°29 1°95 377 4°95 5°41 3°31 4°39 4°85 22°7 18″4 T3°9 19°76 23°26 5°45 5°21 4°95 5°47 11°68 22°68 17°66 4°45 3°59 12°54 4 13°44 5 6 Ig*2 22°79 3 7 9 10 Il 4°32 oO 3°13 Og. 1°75 (e) 5°3 TasLe ILLUSTRATING THE WORKING OF SIMPSON RULE FoR FINDING DiIsPpLACEMENT AND CENTRE oF Buoyancy. I 2 Simpson’s Area, Multiplier. fe) I 2°08 X 4 = = Result, 0 832 x x Oo I = = o 8°32 72 xX 2 = 14% % 2 = 288 13°44 X 4 = 53°76 X 3 = 161°28 5 192 xX 2 = 384% xX 4 BUOYANCY FOR Multiplier. fe) 2 AN ‘ impson’s Area, x are I = INCLINATION Multi- Result. 0 plier. x 0 Result = 6 202 xX 4 = x 1 = 754 X 2 = 15:08 xX 2 = xX 4 = 556 xX 3 19°76 = 166°8 xX 6 2 = 23°26 39°52 X x 2 4 9304 158:08 7 = = 228 X 5 = = 465°2 45°36 3 4 13’9 5 x 2 808 x 6 = 8-08 30°16 272°16 8 17.66 x 9 7 12°54 = X 2 = 25:08 x 8 = 200°64 57 xX 4 = 228 xX gQ = 205’2 t & 10 = 10 Il For ye the 4 x 70°64 xX 77 xX Total = 378-07 displacement 37597 294°48 77 Total= 2008’s x 4 of 4 ins. = 375°97_X 4 =501°29 Therefore the Sisttievenany in cubic ins is 501-29. For the displacement in lbs. a 18’r lbs. = 2008’S + 375°07 Result. 3 4 6 the sections For the position of the centre of buoyancy— Multi- plier. oF OF 20°, I from thesum of the two the area of the “out” wedge. Having obtained the new areas for the inclined angle of heel, it is usual to calculate the position of Section. 1936 + 365°32=5°3 (4 ins. being the distance CENTRE Sec ion, . The last column is obtained by adding to the o-iginal area that of the “in” wedge, and deducting separatcly. X 4 apart) = 21°2, Therefore, the centre of buoyancy is situated 21-2 ins. from section 1, : TABLE FOR CALCULATING THE DISPLACEMENT AND iw 77 give, firstly, the working of the original centre of buoyancy, and, secondly, the centris for the inclined position, and the “in” and “out” wedges 1. The working, therefore, is— TABLE oF AREAS FOR ‘‘EvEN”’ KEEL: “IN” anp “Out” WEDGES: AND FOR INCLINED Position, Area of 607 the boat in cubic inches, viz.: the under water body displaces 487-09 cubic ins. of water. To find the displacement in Ibs., it is only necessary to divide this number of cubic ins. by the number of 1536 5°34 x 4 ins. (the distance between sections =21 *36). Therefore the centre of buoyancy is 21°36 ins. aft of Section No. 1. TABLE FoR CALCULATING DISPLACEMENT AND CENTRE OF BUOYANCY oF THE “ IN” WEDGE. 7 22°77, 22°77 X 4 xX X = 454 XK 18°4 11°68 2 = 903 8 9 4 2 = = xX 73 23°36 6 X x 7 8 = 4°32 186°88 2 X 4 65 = 17:28 X 4 X = 9 26 = 55°52 xX 3 2°29 1 = X 2 = 4958 X 2 = g’I6 4 5 6 3°77 495 5°41 X X X 4 2 4 = = = 15°08 99 21°64 X X X 3 4 5 = = = 45°24 306 108’2 2 4 = = 109 204 6 7 = = 2 = 8 = To 11 fe) xX x © & 16 x 5 10 = 4s4 = 2724 ‘= = 515″2 Oo Total = 365-32 Total= 1936 To find the displacement, the total of column 4, which is 365-32, has to be multiplied by 4 of the distance the sections are apart. In this case it is assumed that these sections are 4 ins. apart, and So 365°32 must be multiplied 4 of 4; thus: 365 °32 X 4 =1461°28 + 3=487°09 And now this figure 487-09 is the displacement of Section, Area. to) 7 8 5°45 S°2I 9 445 10 II 3°38 Simpson’s Multiplier, xX X X X X 77°=X I 4 t Total = = = Result. oO 9 13°52 77 108°73 x x X xX Multiier: pl O x 9 X 10 = = = Total Result, Oo 26 6’54 145’88 71’2 121°68 7°7 616-66 The Model Engineer and Electrician. 608 For the displacement in cubic inches, the total in column 4—that is, 108°73 is mulitplied by $ of the spacing of the sections; therefore, 108°73 x 4x 4= cubic inches contained in the “in’’ wedge, and this result is 144°97. The displacement in “lbs.” will be, as is shown in the other tables, 144°97 “pee . i wnmaa 5°241bs. For the centre of buoyancy, as before, 616°66, 108°73, and the result multiplied by the spacing of the 616°66 xX 4 = 22°68. And so sections. Therefore, the total of the last column, is divided by 108°73 the centre of buoyancy of the “ in” wedge is 22°68 ins, aft from section or BUOYANCY OF THE “ Out”? WEDGE. i) Rezult. plier. Multiplier. Result. Oo x oO = I = 0 4 = 284 xX 1 = 2°84 x 3°31 439 X X 4 5 6 7 8 9 10 Il 195 485 5°47 405° 359 175 fe) Multi- Simpson’s Area. 71 fe) inclination of 20°. Between sections 7 to 8, and 4 to 1, these two curves do not actually coincide, but it is difficult on so small a scale to draw them e two lower curves are, respectively, separately. the curves of displacement of the “in” and “out” wedges. It may sometimes be necessary to raise or lower a boat in the water, viz., to decrease or increase the length of the L.W.L. by the removal of, or addition to, the lead. For this purpose it is useful to know what is termed the displacement per unit To calculate this the e No. 1. TABLE CALCULATING DISPLACEMENT AND CENTRE Section. I 2 X 7°8 X 2 = 39 X 23 == 39°72 4 = 13°24 X X 4 2 = 878 X 4 X 2 = 718 x x I = =194 35°12 = = 97 8 = 57°44 x 10 = X § rule ; the latter is the simpler of the two and quite sufficiently accurate for the present purpose. The reader should be now able to work this area without further instruction, but a table is given to refresh his memory. The rule is, add half the sum of the first and last ordinates to the sum of the other ordinates and multiply by the spacing : No. of Ordinate. xX 6 = 65°64 X 2 = 10°94 *§ 4 = 1973 X JF = 138°6 I 93°08 Total As before displacement in cubic inches = 93°08 08. 4°5 lb: Ss. 240° ay n Ibs, exharts : t iin i Displacemen For the centre of buoyancy Ee X4=21°8. “out” And so the centre of buoyancy of the No. 1 wedge is situated 21°8 ins. aft of section the displacement From these tables it is seen that out Ibs. 181 at works position inclined the for of °5 Ib. against the actual 17°6 lbs., a I matter known that difference. Now, from Chapter it isthat the disthis cannot possibly happen, and really what lbs.; 17°6 be placement must still rise in the would take place is that the hull would lbs. 17°6 the exactly displaced he water unless cD and AB lines inclined the words, other In should have been drawna trifle lower than as shown in Fig. 28. But 4 lb. is not worth considering in 4 = al 7 = 9 10 II I°§2 2°88 = 5 8 7 ° = 6 507°16 Length of Ordinate. = 2 3 X 9 = 63Oo X 4 = 07 Total xeXx4 December 29, 1904. to the inclined position, Curve A is the displaceThe ment curve of the boat on a level keel. 3°92 4°68 5°28 = 55 = 54 = 3°8 : 4°92 = = = Half sum of first and last = 0. oO = 151 ‘6. Sum of other ordinates = 37’9 X 4 151 ‘6 sq. ins, Area of half of the L.W.L. plane = Area of full L.W.L. plane = 151°6 x. 2 = 303°2 ; Supposing now it is required to raise or lower q. ins. by the boat } in. The 303°2 sq. ins. is multiplied75°8 } in., and the result is 75°8 cubic ins.—viz., therefore, if 75°8 is divided by 27°65, the quotient will be the weight in lbs. to be added, or deducted, in this case 2°7 lbs. This this case. is 21°2 ins. The centre of buoyancy on a level keel position it aft of section 1, whilst for the inclined of an inch is 21°36, so it has only shifted about thsatisfactory, n a 40-in. water line, which is quite pressing down of and there should be no serious position. the bow due to this alteration of The various curves of displacement are shown in Fig. 29, and will be seen to be of a very similar nature, thus showing little distortion of body due appetite of the model yachtsman and to encourage him in giving more study to his hobby than that gained by rule-of-thumb methods.