Page:Popular Science Monthly Volume 6.djvu/146

134 Under these curves is placed the notation which represents the pressure of the left diagonal biped. The second impact is given by the feet AD and PG (right diagonal biped), and so on through the whole length of the tracing. Thus the free trot is a pace in which all the four feet give but two strokes, and in which the ground is struck in turn by the two diagonal bipeds; it is also a high pace, the animal being raised for a brief interval between two successive strokes above the ground. The duration of this suspension, according to Fig. 5, is equal to half the time the feet are pressing on the ground. But the trot varies greatly in different horses in this particular, there being oftentimes a very slight period of suspension, although a perfect synchronism of the diagonal strokes of the feet is observed.



By comparing the lines illustrating the reactions with the tracings afforded by the movements of the limbs, it will be seen that the moment when the body of the animal is at the lowest part of its vertical oscillation coincides precisely with that at which its feet touch the ground. The time of suspension does not depend on the fact that the