156 Railways and their Future Development. April, 



Hence it follows that the rolling-stock itself must revert 

 more nearly to its original pattern, readopting those con- 

 trivances which, under altered circumstances, were discarded. 



Still keeping to the most elementary principles, for 

 it is these which are forgotten and misunderstood, and 

 yet they should be engraven on brass and hung up 

 in every railway board room in the world. On a 

 common road, a horse can pull a ton weight in a cart 

 behind him on the level at 4 to \\ miles an hour, or, 

 which is the same thing, if a weight of 70 lbs. were hung 

 over a pulley and lowered down a well, he could pull 

 it up at the speed mentioned. It is necessary to be a 

 little explicit, as the remarks in this paper are intended 

 for non-technical readers particularly. Now if two strips 

 of iron called rails are laid upon the aforesaid road, 

 the friction is reduced seven-fold, that is to say, the same 

 horse at the same speed could draw 7 tons, the difference 

 between macadam and iron being as 70 lbs. to 10 lbs. 

 This immense advantage, however, disappears when gra- 

 dients have to be encountered, because the resistance 

 due to gravity becomes so greatly in excess of the resist- 

 ance due to friction, and is constant in both cases. For 

 instance, if on a common road, up a slope of one foot 

 in ten, the horse takes 5 cwts. in a cart over the macadam, 

 if rails be laid down up the same hill, he could only increase 

 the burthen behind him by a little more than 1 cwt., 

 or, in all, 6J cwts. ; hence, in this case, the value of the rails 

 is nearly lost. Hence the small use of tramways where 

 hills occur. 



Upon a very good macadamised road the resistance due 

 to friction is usually taken at about one-thirtieth of the whole 

 load carried ; that is to say, if the vehicle were put upon a 

 road sloping 1 in 30 it would just begin to move of itself. 

 But upon a railway, under the most favourable conditions, 

 the resistance due to friction has been reduced to the two-hun- 

 dred-and-eightiethpa.vt of the whole load carried; that is to say, 

 the vehicle will begin to move of itself on a gradient of 1 in 280. 

 In considering the work which a horse can perform on a 

 tramway, it is important to bear in mind the question of 

 speed ; for, according to the experiments of Tredgold, he 

 can draw exactly four times as much at two miles an hour 

 as he can at five, and it appears that at three miles an hour 

 he does the greatest amount of actual useful work, whereas 

 at ten miles an hour only one-fourth of his actual power is 

 available, and he cannot exert that for an hour and a half ; 

 whereas at two and a-half miles an hour he can continue 



