108 FARM ANIMALS 
longer. In horses, levers of the first class are always 
levers of speed. 
5. How a horse moves.—In the horse, levers of the first 
and third class are levers used for producing motion. A 
simple illustration may be found in the movement of the 
arm about the point of the shoulder. Muscles of the 
shoulder, A D, attached to a projection on 
the arm bone, are enabled by contracting to 
rotate the arm and leg forward. The fulcrum 
is at B. It isa lever of the first class. Mus- 
cles, D C, lift the foot from the ground, pre- 
paratory to being moved forward by the 
muscles, A D. The fulcrum is at B. The 
power arm is represented approximately by 
the line B C, while the resistance arm is ap- 
proximately the line B E. It is, therefore, a 
lever of the third class. The more nearly the 
How a Hornse arm A E is at right angles to the shoulder 
Moves BD, the more powerful the horse will be. 
The greater the angle of shoulder with the arm the 
greater speed will the horse be capable. Horses having 
large joints are powerful horses, because the power arms 
of the levers are longer in proportion to the resist- 
ance arms. 
6. How a horse stands.—It is natural that 
a horse should wish to stand with the least 
possible effort. This is accomplished by using 
a lever of the second class, which is always a 9 
lever of power. When a horse stands prop- ¢ 8 
erly the weight of the body descends directly 
down the cannon through the fetlock to the How a Horse 
ground. The fulcrum, F, is in the foot, while a 
the power which prevents the fetlock from touching the 
ground and thus sustains the weight of the ‘body is 
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