come this resistance, which varies from a hundred to a hun- 

 dred and fifty, and keep up the motion unimpaired, a power 

 must be applied equal to that of the resistance. • Wherefore 

 it is, that when an additional weight is attached behind him, 

 to be moved by traction on a level, a part of his natural weight 

 is pressed against the collar and traces, sufficient to overcome 

 the resistance of the load. His remaining muscular force is 

 employed to keep up the motion thus produced. The natural 

 power of the animal thus divides itself into pressure to move 

 his load, and muscular action to move himself in this state. 

 The total power or strength of every horse having natural 

 limits, it is evident, if the pressure is increased beyond its just 

 limit, it must be at the expense of the muscular power, which 

 will thus be untimely exhausted, and the utility of the animal 

 destroyed before its natural period has expired. At 20 miles 

 a day/ he may drag a certain load every day for many years : 

 if made to exceed that amount of labor he will be sooner worn 

 out. We are therefore so to use a horse as to get as much 

 beneficial effect from him as we can, at a speed which will 

 not injure him. Hence arise the important inquiries ; what 

 ought to be every day's duration and extent of a horse's work, 

 and how much load ought he to carry ? It is found by calcu- 

 lation, that the maximum of speed of an unloaded horse for 1 

 hour in every day is 14. 7m. on a level ; and that his maxi- 

 mum of speed when loaded, is one half of his unloaded velo- 

 city. Thus if an unloaded horse can. gallop one hour every 

 day, at the rate of 14 miles and seven tenths, he can draw 

 his load half of that distance in the same time. 



The following table, extracted from Wood, gives the law 

 of the decrease of speed of an unloaded horse at his maximum 



This computation is 1»umm1 upon the natural powers of a 

 useful horse, and shows the performances he can, when unload- 

 ed, do every day without injuring himself. Thus, although at 

 his greatest speed for one hour, he can go 14. 7. m. still if his 

 maximum speed is kept up for 6 hours every day, it will be at 



One hour ir 

 2 do 



3 do 



4 do 



5 do 



6 do 



7 do 



8 do 

 10 do 



do 

 do 

 do 

 do 

 do 

 do 

 do 

 do 



14 7 

 10 4 



8 5 

 7 3 

 6 6 

 6 0 

 5 5 

 5 2 

 4 6 



