In leaping, the Motion of a Mans Head, is thrice as quick as that of his Heel, before the tip of his Foot, quit the Ground; and twice as quick as that of his Flanks. This diversity is owing to the opening and straightening of three several Angles, at the same time; the highest of which, is that formed between the Trunk and the Thighs, forwards; the second that of the Thighs in their Joncture with the Legs, backwards; and the third is that forwards, which the Legs form, with the Bone of the Feet.