THE AUTOCAR B Journal publtsbeb in tbe interests of tbe mecbanicall~ propelleb roab carriage.

EDITED BY H. WALTER STANER.

No. 550. VoL. XVI.]

SATURDAY, MAY 5TH, 1906.

[PRICE 3D.

TlfE AUTOCAR.

(Published Weekly. )

Registered as a newspaper for transmission in the United Kingdom.

Entered as second-class matter at the New York (N.Y.) Post Office.

EDITORIAL OFFICE :

COVENTRY.

PUBLISHING OFFICES :

20, TUDOR STREET, LONDON, E.C.,' ENGLAND.

CONTENTS.

PAGE

NOTES : BORE AND STROKE-PR'-CTICAL CONStDERATIONS-A STANDARD

SIZE FOR LAMP BRACKETS

563-564

USEFUL HINTS AND TIPS : MAKESHIFTS ON TOUR {illustrated ) .. . 565 THE HOTCHKISS CARS !illus t ra t ed) 566-568 A ERONAUTICAL NOTES ... 568 ON THE RoAo. By Owen John ... ... 569 THE 4,000 Mrus TYRE TRIALS: JuDGEs' REPORT... 570-571 MORE ABOUT THE AUSTIN CAR (illustrated) ... 572-574 THE GRAND PRIX A:RuN ON AN 18-22 H.P. RoCHET-SCHNEIOER THE GLADIATOR COMPETITION ... CONTINENTAL NOTES AND NEWS: THE ELASTIC WHEEL T RIALS

574 575 575

(illustrated)-THE TARGO F LoRro- MrLAN A.G. GOLD CuP-AIR·

COOLING FOR CAR ENGINES (i llustrated)...

576-577

AN INTERESTING FuNCTlON

... 578

CORRESPONDENCE: CUBICAL CONTENT!-; ANO H ORSE-POWER-BALANCING

OF PETROL ENGINES-BALANCE GEAR AND ITS ACTION- RUNNING COiiiTS-THE AUTOMOBILE ASSOCJATION-PRJCES OF MOTOR CARS IN Nxw ZEALAND-!:5 UMMARY OF CORRESPONDENCE 579-582 THE KORTING PARAFFIN ENGINE tillustrated) 583-564

ENGINE TESTING

To SEcURR DusTLEss Ro1ius FLASHES .. .

... 584

... 584 585-588

CLUB DOINGS : C LUB FIXTURE~-HEREFORDSHIRE A.C .-KE"N~INGTON

A.C.-AsHBY-DE-LA-ZoucH lNTt!.R-CLU B ME!!T- BLACKHEATH A.C. - SOUTHERN M.C.-ScoTT1 SH A .C. - YoRK~H1R .. : A.C.- NORTHEAsT LANcs. A.C.-MAr-CHESTER A.C.-SouTH WALES AND MONMOUTHSHIRE AC -IRISH A.C.-M OTOR UNION MEt!.T AT BIRMINGHAM-BRITISH .MOTOR B OAT CLUB 589-590 SOME Q UERIES AND REPLIES 591 ANOTHER INDIRECT FOURTH 592 HEIDELBERG-HONIGSTUHL HILL-CLI MBING TEST 592

"THE AUTOCAR " SUBSCRIPTION RATES: t,ritisb Isles, 16s. Abroad (thin paper edition), 22s. 8d. lJer arn1um ..

(e a,d S1rnkeN ote We recently published a contribution from a wr;ter who mainta ined that, speaking broad ly, the one thing which determined th e po1rer of an engine was its size. Now thi s contribution has p roYoked some \·ery strong protests, as our corresrondence columns show. We have no intention of throwing open our columns to a protracted discussion of t he matter, because we do not think it would result in any defi nite concl us ions being reached at the present time, 1rhe:1 such a wide d ispar ity in the pmrnr claimed for engines of similar dimensions is common. It shou Id be understood that we do not infer by this that the rnst majority of makers a re selling engine of less horse-po1yer than r la imed. The real d ifference is that one maker calls his engine, say,

20 h.p. , and that is about its limit. On the other hand, the maker of a n engine of similar dimensions only ra tes it as 15 h.p., though it is capable of runn ing up to as high a p011·er as the first engi ne named. ln other 1rords, some makers choose to ca ll the ir P.ngi nes by about their maximum horse-po wer ; others p refer to ra te them a t twenty-fi1·e per cent.. or e1·en fo rty per cent., belo1r it. At the same t ime. it must be admitted that th is disparity is very ba ffl ing to a good many. as a t first sight it appears strange that one car 11·it h a mur h la rger engine than another should only be of th e same nominal po1rer.

On this ubject our con tributor maintained that, in the main. re,·olutions per minute roulcl be ignored, and this is where he has gone too fa r. E 1·ery engine has its cri t ical speed . and beyond this speed it can be made to revolve faste r, but it ,1·ill not giYe more power, and if the speed is st ill furth er increased the p01rer wi ll fall off. On the ot her hand, it is equally true that an engine of. say , a normal speed of 800 re1·olutions per minute can I e accelerated up t o- 1 ,000 or more, and will continue to gi\·e more power righ t up to the 1 ,ooo. At some number of tu rns per minute abo,·e this its pm1·er will begin to fall off, a nd a speed will be reached 1rhen it will merely ha,·e the facil ity for turning round at a. great speed , and doing lit t le or no useful work. H orse-power may be r a tc ul ated, but the hrak,e test is the only one 11·hi ch i 1rnrth anything otbe1 than actual trial on the road. wh ich is e1·en more conYincing, and ,ri thi ;1 certa in limi ts it must be admitted that under road cornlitions the big engi ne te l!s. Other things being equal, the larger o f two engines 11·ill be the more pmrerful, and consequently the car 1Yill be a faster ancl better bill-climber, but here aga in the ext reme is soon reached. a beyond a certain limit other things cannot be equal. ft is equally necessary to bear in mind that it is pe rfectly possible, and , as a matter of far t. it is done every clay, to make an engine sma ll er than another which develops the same power on the brake, the smal ler engine. we will say . at r.200 re1·olution~ per minute, and the la rger at 1 ,000 r. p. m.

Practical Considerations. :-( 011· either of tbes type of engi:1e may be mad"" ~suitable fo r use upon a mot ,r car. the small engine y making it so small that it s ra te of re,·olut ion . or rather its piston speed, is so high as to be impracticable, or tlw la rge one by mal.; ing it so big that its rate of re1·olution has to be uncluh- reduced . ,o the best practice, like a ll other engin'eering matters, is a compromise, in th is ea e a compromise bet11·een the small and 1·ery high-speed engine and th e la rge and s luggish -~ngine. r n most ca~es the matter is 1·iewecl from c'"xtrem--:' and opposite standpoints. o,~e school of motorists maintains that v: ithin li mits it is impossible to make an engine which runs too fast : the othe r one maintai ns that size and ize a lone is ,rhat is wanted. So long as there i~ a big engine. and th erefore p lenty of pO\rer in hand , all will be \r e l l. As we ha1·e said, the be t compromise li es between these t1,·o extremes, hut a t the present time there is not suffi cient expe ri nee