THE HORSE 357 



A riding horse carries on an average from 100 to 

 175 kilograms at a slow gait. If the load is a rider 

 of 80 kilograms, the horse can travel seven hours 

 and cover ten leagues of four kilometers each. But 

 its strength is much better employed if instead of 

 carrying the weight on its back the animal draws it 

 in a vehicle. Then an expenditure of energy repre- 

 sented by the weight of five kilograms is sufficient 

 to move a load of 1000 kilograms if the wheels of 

 the vehicle run on a railway track. For the same 

 load on a smooth, level road an expenditure of en- 

 ergy represented by 33 kilograms is needed; finally, 

 if the road is paved with stone the required energy 

 will be 70 kilograms. On an excellent road, stage- 

 coach horses draw each a load of 800 kilograms and 

 cover six leagues in two hours, after which they are 

 replaced by others. 



4 'Let us compare these figures once more with 

 those relating to the steam engine. A passenger 

 locomotive draws with a speed of a dozen leagues 

 an hour a train having a total weight of as much as 

 150,000 kilograms. A freight locomotive draws at 

 the rate of seven leagues an hour a total weight of 

 650,000 kilograms. More than 1300 horses would be 

 needed to take the place of the first locomotive, and 

 more than 2000 for the second, if they were used to 

 transport similar loads the same distance at the 

 same rate of speed, using cars running on rails. 

 How many more would be needed with wagons on or- 

 dinary roads, where the surface inequalities cause 

 such waste of energy ! 



