There is another peculiar feature in the walk of the chimpanzee. The motion of the arms and legs do not alternate with the same degree of regularity that they do in man or quadrupeds. This ape uses his arms more like crutches. They are moved forward, not quite, but almost at the same instant, and the motion of the legs is not at equal intervals. To be more explicit: the hands are placed almost opposite each other; the right foot is advanced about three times its length; the left foot placed about one length in front of it; the arms are again moved; the right foot again advanced about three lengths forward of the left; and the left again brought about one length in front of it. The same animal does not always use the same foot to make the long stride. It will be seen by this that each foot moves through the same space, and that in a line, the tracks of either foot are the same distance apart, but the distance from the track of the right foot to that of the left is about three times as great as the distance from the track of the left foot to that of the right; or the reverse may be the case. The distance from the track of either foot to the succeeding track of the other, is never the same between the right and left tracks, except where the animal is walking at great leisure. There is, perhaps, no animal more awkward than the chimpanzee, when he attempts to run. He sometimes swings his body with such force between his arms as to lose his balance, and falls backward on the ground. I have often seen him do this, and when he would right himself again, would be half his length farther backward than forward of his starting-point. The chimpanzee is doubtless a better climber than the gorilla. He finds much of his food in trees, but is not arboreal in habit in the proper sense of that term. To be arboreal, the animal must sleep in trees or on a perch, but the chimpanzee cannot do so. He sleeps the same as a human being does. He lies down on the back or side, and, as a rule, uses his arms for a pillow. I do not believe it possible for him to sleep on a perch. He may sometimes doze in that way, but the grasp of his foot is only brought into use when he is conscious of it. I have often known Moses to climb down from the trees and lie upon the ground to take a nap. I never even saw him so much as doze in any other position.