THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. [Skptkmbbk, 



366 



j_ ir. tht> inrh tlu' extraction of two-thirds of 

 r'buTk'f'rKtestthingtotirmotioo of the train. We 



%re"reS/rollary to this statement is that the train is pro- 



that estimated above-that is to say. one-fifteenth instead ot two 

 n-^it raSiy'^oleXrthe friction of the Fjemng PUton 



S"l Unguage'a fZtn of two variables-that is, varies as the 



^-iiCl^'^i^^^^^^^ e^haustio. 

 Before d1 cussing the next cause of loss of power, we may consider 



^^"Soseo eY^a^^^^^^^ 



m T^hird method of traction was based on two bydrosta Uc 

 • . .io* «i;» T,rP«ure of water is d rectly proportional to its 



ntfinllKS: llelZl if clmunicated eqUly'in every direc 



tion. Hence if a cistern A con- !i I 



taining water communicate by a 



tube of any form whatever with a 



piston B fixed in the tube, the pres- 



sure on B will not depend on the 



quantity of water in the cistern and 



tube, but solely on the perpendicu- 

 lar altitude of the surface of the 

 water in A above B. In the case 

 of the railway, the piston B was 

 attached to the train, and was to ^^^^ 



.hole »». of «»l "°P"°^l'' ;,iSo°.rr.nlb" m.dtlo'm 



one gasometer, the gas being obstructed in nowing oy 

 *'^Eitr;^Src;£:rffi the comparison between the 



hytuf a^n] aUspheric railways -- /-f ^ "J::,7ti^ o't 

 former. Water being incompressible (nearly s°' "„'./';•; ';ded in 

 corresponding to thaffrom " Preliminary exhaustion ^ is avoided n 

 the hydraulic scheme; owing to^^ter being much less ™ 

 air, the waste from leakage would also be niuch less. The J^y^; \^ 

 system affords also the convenience of a «s"^°" f .?°!'"^ „{ time 

 power stored in the cistern may be employed at any distance 

 after the cistern has been filled. intervention of air 



The last effect of transferring pressure by the intervention u 

 ,,hich we have to consider, may, like the pre^dmg' ^e e^f '£^1% 

 analogy. In considering the rope traction it was shewn tHatoDsia 

 on tlJ^rails would cause -a constant stretching ^"'l "°^J, «"^^^,^^fer wiU, 

 rope, which would give rise to a waste of P°^". Thejeadej w^^^^ 

 on reflection, easily perceive that the same waste occurs in atmospne 



ric tracUon. only proportionably increased, on account of the exceed- 

 ingly grea?« elasticity of the materials by wbi.h communication of 



^°IV in theloith mode of traction, that by locomotive engines, the 

 cauTesof lossof power diflTer altogether from the preceding-they 

 arfse from the power being employed in moving no only the train, 

 h«t also The enormous additional weight of the engine and tender, 

 which frequeJy amounts to fifteen tons, also from the occasional 



''^tJeXl rrSrsoutlon^ss of force in the three methods of 

 raiTwav conveyance. In making, however, an election between the 

 hre^niZ other questions besilles that of loss of power would have 

 to be trkenintoaccount._suchas the danger of breaking the rope, 

 where that kind of traction was used; and, on the other hand, the fact 



f hP mere ouestion of waste of power, there will be no diftculty m ae 

 ermTning??rom the above considerations, the particular mode of trac 

 ti on in which the loss immeasurably preponderates. ^ ^ 



STEAM RIVETTING MACHINE. 

 In onr last volume, page 216, we gave an engraving of Mr. Fair- 



SS=jpjpi^'S^trs?r?,r.ts 



Fig. 1. 



^ F'S- 2 



II 



'^^:n:5%sp^^^ 



^^^^^^^Si 



view- fie. 2. front view of the top of stem ; fig. 3, a plan of the ma- 

 S; fi?. 4 section through the*^ steam cylinder ; figs. 5 and 6 plan 

 and Vide ;iew of the piston; similar letters in eacS figure refer to 

 similar parts. 



Kg. 3. 



„AS?>T3,"t-is.SLXSiStx^.rip"^r 



