ON RAILWAY CONSTANTS. 



261 



The engine, it might be supposed, would act as a sort of cut-air to throw 

 aside the current, and break its force before it reached the flat surface of the 

 carriage. However improbable such a consequence might be after the indi- 

 cations just recorded, where a still more decided change of form was made 

 the subject of trial, it was nevertheless determined to put the case to actual 

 experiment. Accordingly a four-wheeled engine, the "Fury" and its tender, 

 were weighted equal to two carriages. The pistons, connecting rods, and 

 other working gear of the engine, were detached from the driving wheels, so 

 that the engine should be subject to no other friction save that to which a 

 carriage is subject. The grate-bars, ash-pan, &c. were removed, in order to 

 make the engine as light as possible, and to assimilate its weight to that of a 

 loaded carriage; two carriages were also prepared of equal weight. The 

 Fury and tender were first dismissed down the Sutton Incline ; afterwards 

 the two carriages, and their times of descent compared. 



The following is an abstract of the performances recorded in Tables 

 XX. XXI. :— 



The differences, as will be seen, are extremely slight. Each train was now 

 increased by four carriages, and the contest took place between a train con- 

 sisting of the Fury tender and four carriages, and a train of equal weight, 

 consisting of six carriages. Tables XXII. and XXIII. may be referred to. 

 The following is an abstract : — 



Here again there are no greater differences than might be expected with 

 an experiment repeated twice over with the same train, and we may fairly 

 conclude that the form of the front has no observable effect, and that whether 

 the engine and tender be in front, or two carriages of equal weight, the resist- 

 ance will be the same. 



It has already been shown that at equal speeds, tlie excess of resistance, 

 after deducting the friction, does not increase in the ratio of the load; a 

 train of six carriages, at twenty-nine and a half miles, having experienced 

 only one and a half times the. resistance that a train of half that size at the 

 same speed was subject to. This fact pointed to the conclusion that the 

 excess of resistance observed at high speeds was due to something besides 

 the mere extent of frontage, and this conclusion was confirmed by the ex- 

 periment we are about to cite. 



