252 KIGHTH REPORT 1838. 



tion already of such trifling amount. The adoption, therefore, 

 of hirge wheels, of expensive lubrication, of friction i-ollers, 

 and of other similar contrivances for reducing the amount of 

 friction, Mill be clearly unadvisable, since such expedients wou^d 

 be attended with much more expense and inconvenience than 

 M'ould be adequate to any effects they could prodilce in dimi- 

 nishing a resistance already so small. 



The importance of low gradients will be diminished. The 

 advantages supposed to attend these are founded on the suppo- 

 sition that the tractive power upon a level requires so great an 

 increase when a moderate gradient is ascended, that either a 

 superfluous moving power must be provided on the level, or that 

 the moving power adapted to the level will be overstrained in 

 ascending the gradient. So long as the resistance on a level is 

 estimated at eight or nine pounds a ton, a gradient rising at the 

 rate of eighteen or twenty feet a mile will require the power 

 to be doubled ; but if the whole resistance on the level be con- 

 siderably greater, and the proportion of it due to friction be small, 

 then a much steeper inclination would be necessary to double 

 the resistance to the tractive power ; and, on the other hand, a 

 small diminution in the velocity of the train would compensate 

 for the increased efi"ect from gravitation. In laying out lines of 

 railway, therefore, intended exclusively or chiefly for rapid pas- 

 senger-traffic, instead of obtaining by a large outlay of capital a 

 road nearly level, steeper gradients would be adopted, and the 

 resistance to the moving power rendered sufficiently uniform by 

 variation of speed. That this has been in fact practically ac- 

 complished on some of the more extensive railways now in 

 operation in this countrj', is within the knowledge of some of 

 the Members of this Committee ; and it is hoped that in a 

 subsequent Report they will be enabled to prove it by pro- 

 ducing the actual results of such experience. 



If it shall appear, as now seems at least probable, that in 

 railway traffic conducted at high speeds the cliief part of tlie 

 moving power is engrossed by the atmospheric resistance, it 

 Mill be a matter for serious consideration how this resistance can 

 be diminished ; and it is evident that, ceteris ])ai'ibus, wide 

 frontage, and therefore increased gauge is disadvantageous. 



These are points to the investigation of M^iich the Committee 

 will hereafter devote attention, and it is hoped they will be 

 enabled to lay before the Association such experiments and such 

 results of the practical traffic on railways, as will justify distinct 

 and satisfactory conclusions upon them. 



