newcomer sets an electric bell ringing; and this signal continues all the time the bird remains in the trap; thus giving notice to the sergeant of the guard, who takes the despatch and forwards it to headquarters. The liability of so defenceless a bird as the pigeon to attack has led to experiments being undertaken from time to time with young ravens, which make fairly quick and reliable messengers up to a distance of about fifty miles. As the raven is very teachable (it can be made to "retrieve" most creditably), and as it manifests a strong attachment to its birth-place, there seems no reason why its training should not be further extended in the new direction, for which its great spirit and endurance appear eminently to fit it. Here I have only touched upon the speed and power of flight, but the whole subject is one of the most fascinating branches of natural history. No reference has been made to the marvellous movements of birds in the air, which constitute the very poetry of motion--the stationary balancing, hovering, circling, and gliding, all of which may be observed, especially among our own birds of prey. Although much is known of the speed of birds and animals, there are but few ascertained facts concerning that of insects and fishes. The comparatively low intelligence of these two classes of animals makes it difficult to direct them. They rarely fly or swim in anything approaching to a straight line, and experiments give only approximate results. Pike in pursuit of their prey seem to flash through the water; and salmon and trout move almost as quickly. The Spanish mackerel, with its smooth, cone-shaped body, is among the swiftest of fishes, and for speed only finds a parallel in the dolphin. There is a great similarity in shape between these two, and both cut the water like a yacht. The first follows the fastest steamers with the greatest ease, in its dashes swimming at five times their speed. The bonito is also a fast swimmer; and all those fishes "trimmed" in like fashion with him.