Destructive though the Eagles may be, they cannot be called cruel birds, for, although they deprive many birds and beasts of life, they effect their purpose with a single blow, sweeping down upon the doomed creature with such lightning velocity, and striking it so fiercely with their death-dealing talons, that almost instantaneous death usually results. When the Eagle pounces on a bird, the mere shock caused by the stroke of the Eagle's body is almost invariably sufficient to cause death, and the bird, even if a large one--such as the swan, for example--falls dead upon the earth with scarcely a wound. Smaller birds are carried off in the talons of their pursuers, and are killed by the grip of their tremendous claws, the Eagle in no case making use of its beak for killing its prey. If the great bird carries off a lamb or a hare, it grasps the body firmly with its claws, and then by a sudden exertion of its wonderful strength drives the sharp talons deep into the vitals of its prey, and does not loosen its grasp until the breath of life has fled from its victim. The structure by means of which the Eagle is enabled to use its talons with such terrible effect is equally beautiful and simple, deserving special mention. Now, many observant persons have been struck with the curious power possessed by birds which enables them to hold their position upon a branch or perch even while sleeping. In many instances the slumbering bird retains its hold of the perch by a single foot, the other being drawn up and buried in the feathers. As this grasp is clearly an involuntary one, it is evidently independent of the mere will of the bird, and is due to some peculiar formation. On removing the skin from the leg of any bird, and separating the muscles from each other, the structure in question is easily seen. The muscles which move the leg and foot, and the tendons, or leaders which form the attachment of the muscles to the bones, are so arranged that whenever the bird bends its leg the foot is forcibly closed, and is opened again when the leg is straightened. A common chicken, as it walks along, closing its toes as it lifts its foot from the ground and spreading them as the leg is unbent, cannot do otherwise, as the tendons are shortened and lengthened as each step is taken. [Illustration: EAGLES.] It will be seen, therefore, that when a bird falls asleep upon a branch the legs are not only bent, but are pressed downwards by the weight of the body; so that the claws hold the perch with a firm and involuntary grasp which knows no fatigue, and which remains secure as long as the pressure from above keeps the limbs bent. To return to the Eagle. When, therefore, the bird desires to drive his talons into the body of his prey, he needs only to sink downwards with his whole weight, and the forcible bending of his legs will contract the talons with irresistible force, without the necessity of any muscular exertion.