ECONOMY OF RAILWAY LOCOMOTION. i 47 



little explicit, as the remarks in this paper are intended for non-tech- 

 nical readers particularly. Now, if two strips of iron called rails are 

 laid upon the aforesaid road, the friction is reduced sevenfold ; that is 

 to say, the same horse at the same speed could draw 7 tons, the differ- 

 ence between macadam and iron being as 70 lbs. to 10 lbs. This im- 

 mense advantage, however, disappears when gradients have to be en- 

 countered, because the resistance due to gravity becomes so greatly in 

 excess of the resistance 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 cwt. in a cart over the macadam, if rails be laid down up 

 the same hill, he could only increase the burden behind him by a little 

 more than 1 cwt., or, in all, Q\ 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 macadamized 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 fa- 

 vorable conditions, the resistance due to friction has been reduced to 

 the two-hundred-and-eightieth part 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 tram- 

 way, it is important to bear in mind the question of speed ; for, accord- 

 ing 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, be 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 working for eight hours. 

 Having these data before us, it is easy to compare the values of steam 

 and horse-flesh : Suppose coals to cost in the midland districts 18s. 8c?. 

 a ton only, or one-tenth of a penny per pound, and, assuming that an 

 average locomotive-engine will not consume more than 5 lbs. of conl in 

 the hour per horse-power, the cost of fuel per horse-power will be a 

 halfpenny per hour. Taking the value of the horse's provender at 

 Is. 9d. a day only, and supposing he works for six hours, that would 

 cost Z\d. an hour against a halfpenny in the case of steam, or, as 7 to 1 

 in favor of steam; and this result is obtained on the supposition that 

 the horse travels only at three miles an hour. 



Now, to sum up the combined advantages, therefore, of an engine 

 on a level railway against a horse on a level common road at 10 miles 

 an hour, we shall find that the former gives an economy over the latter 

 of nearly 300 to 1 ; at 5 miles an hour, it would stand as 115 to 1 ; 

 and, at 2^ miles an hour, as 64 to 1. 



Such are the enormous advantages of steam and rails, and with 

 them does it not seem astonishing that better financial results have 



