554 



RAIL-HOADS. 



- 4 1 



Alii 1 1 1 I "> , >? i 



Ibs. to.,,. 



Ahorse at 2 in. exerts usually 112 draws on a level rail road about 10 

 75 6| 



s'.'Ht it>v/f 6. 5 ^ 



g [;>vfi <*ilJ 1'^ a no g, 



8 . Qvaa \itdttgf.i .JfifU -itiorf *q 25 



The friction, therefore, of a ton upon a rail-road is about 

 eleven and a half pounds. It has in recent practice been 

 reduced to nine pounds. 



On a rail-road the usual travel of a horse at two miles 

 per hour, is about twenty miles per day, and his draft, 

 therefore, equal to 200 tons for one mile, or the tractive 

 power exerted one two hundredth part of the weight 

 moved. 



In this country we may estimate the ordinary travel or 

 work of a horse at one third of a ton weight, or at two 

 and a half miles per hour, on the best roads about two 

 thirds of a ton weight, or one twelfth part of that on a rail- 

 road. The draft or tractive force exerted on roads is 

 equal to about one fourteenth part of the load. 



5. In wuiter the resistance is as the square of the velocity. 



6. On a canal one horse at the most draws thirty tons 

 at the rate of two miles per hour, and only one ton at six 

 miles per hour. This rapid decrease of horse power on 

 a canal compared with a railway, will appear more strik- 

 ing, thus : 



J\ files. 

 One horse at 2 per hour draws 



Tons. Jlfilca per hour. 



30 require at 



3 

 4 

 5 

 6 



At three and a half miles per hour the two are equal. 



