ON MAN AND ANIMALS. 
515 
At a walk, a movement of 4 feet of speed (or distance) 
is equivalent to 100 lbs. of burthen 
At a gentle trot of 8 feet to 200 lbs. of burthen • 
At a swinging trot of 12 feet to 300 lbs. of burthen 
At a gallop of 16 feet to 400 lbs. of burthen 
At a swinging gallop of 20 feet to 500 lbs. of burthen 
At a racing pace of 24 feet to 600 lbs. of burthen 
As strength is the originator of speed, so also it has relation to 
the weight of the body. Therefore it follows, from the example 
above given, that a horse carrying a weight of 500 lbs. requires, to 
transport it the distance of a foot, to make an effort equivalent to 
25 lbs. about a twentieth of his own weight ; we may also admit, 
as a general rule, that the expenditure of a horse’s strength calls 
for the twentieth of the weight of his body for every foot of speed 
or distance. 
In order, therefore, to determine in a horse of ordinary work the 
ratio of speed to weight super-imposed, we will take the calculation 
made for a moderate-sized saddle horse, whose strength does not 
ordinarily extend beyond the limit of from 200 to 600 lbs. weight, 
and so, according to what has been laid down, we may conclude 
that, on an average, the horse who expends his strength equivalent 
to 100 lbs. of weight, to clear a space of 4 feet at a step, will not 
make such movement with facility should the weight of his burthen 
exceed 100 lbs. ; and therefore that, mounted by a dragoon whose 
weight may be estimated with his arms and baggage at 200 lbs., 
the same horse will have to carry a weight equal to 300 lbs., one 
to which he may for a sufficiently long time oppose resistance by 
going but at a foot pace. 
Put into a gentle trot equivalent to 8 feet of speed = 200 lbs., 
the horse will have to exert himself under a burthen of 125 lbs., 
which on his part will require a force = 425 lbs. ; so that the 
animal with a weight of 200 lbs. = 500 lbs. of expended strength 
will not be able to resist such a trial beyond a very moderate con- 
tinuance of exertion. 
The gallop, or sixteen feet of speed = 400 lbs. of expended 
strength, occasions the same fatigue as 525 lbs. of burthen. The 
same horse loaded to the extent of 200 lbs. = 600 lbs. of expenditure 
of strength, Avhich is the maximum, soon succumbs from exhaustion. 
The full gallop, the hunting or dispatch gallop, or twenty feet of 
speed = 500 lbs. of strength, does not permit the burthen being 
carried beyond 100 lbs. weight ; and when we come to the race , 
calculated, as it is, at the 24 feet of speed = 600 lbs. of expended 
strength, that excludes, as it were, all burthen ;* since, to make an 
effort equivalent to a space of 24 feet, the horse is compelled to 
expend the maximum of his strength 
