Birds are useful to man by their feeding on the insects, larvæ, and caterpillars which infest cultivated crops. Without their aid, agriculture would become impossible. In former times it was a favourite doctrine with the agriculturist that the _Passerina_ were the real destroyers of his crops, and a war of extermination was declared against them; but the observations of more enlightened persons have demonstrated that the chief food of most of these consists of insects, and the havoc among them has consequently been stayed; still much ignorance, and its concomitant, cruelty, exist on this point. Elsewhere, those interested soon discovered that the destruction of small birds led to formidable increase in the numbers of voracious insects--that these lively and joyous creatures, which float in the air and twitter on the bough, are sent us more for good than evil, and that if some of them make the crops pay a tax, they repay it tenfold by keeping down the excess of more destructive ravagers. While the smaller birds have proved essentially beneficial to man, some of the larger birds exhibit similar tendencies. The Wading Bird clears the earth of serpents and other unclean and venomous animals. The Vultures and Storks throw themselves in flocks on corrupt carrion, and divest the soil of all putrefying objects: thus, in concert with insects, birds are the scavengers of the earth, lending their aid to make it a fit residence for man; in fact, are constituted by nature guardians of the public health. In former days Falconry afforded a stately and picturesque sport to the great, in which lords and noble dames assisted. This pastime still exists in some parts of England and some portions of the East, especially in Persia, where the Falcon is trained to chase the Gazelle and small ruminants; while in China and Japan the Cormorant and Pelican are taught to fish the rivers for their masters. From very ancient times, the Carrier Pigeon was the bearer of messages now transmitted along the electric wires with lightning speed.