The ostrich, that may be considered a connecting link between birds and quadrupeds, is gifted with powerful digestive organs, and is known to swallow stone, glass, and iron; but this faculty appears to be a gift of all-bounteous Providence, to enable the creature to digest the various substances it meets with when traversing burning deserts for hundreds of miles, when these hard bodies actually perform the function of teeth in the animal's stomach, by aiding the comminution of its indigestible food. The structure of the ostrich has a near resemblance to that of the camel, destined to perform the same dreary journeys. The wings are not designed for flight, and in speed he equals the horse. Adanson affirms that he had seen two ostriches at the factory of Podore, that were broken in to carry single or double riders, and the strongest and youngest would run more swiftly with two negroes on his back than the fleetest racer. Spallanzani endeavoured to prove that the pebbles and gravel swallowed by various birds were of no use in the process of digestion; but Hunter, who had found two hundred pebbles in the gizzard of a turkey, and one thousand in that of a goose, demonstrated their utility in the trituration of their food, since these birds were found to be unable to digest, and consequently to thrive upon their nourishment when deprived of this mechanical aid. It is curious that the owl, which easily digests meat and bones, cannot be made to digest bread or grain, and yet dies if confined to animal food. The eagle, and other birds of prey, can dissolve both. A singular process of digestion is observed in the stormy petrel, which lives entirely on oil and fat substances whenever it can obtain them; but when fed with other articles of food, Nature, true to her laws, converts them into oil; the bird still discharges pure oil at objects that offend him, and feeds his young with the same substance. The petrel must, no doubt, be a bilious subject, for he delights in misery, and his presence is a sure presage of foul weather to the experienced seamen; and when The wrathful skies Gallow the very wanderers of the dark, And make them keep their caves, he is seen riding triumphantly on the whirlwind, and skimming the deepest chasms of the angry waves. This bird is said to be named 'petrel' from Peter, since, like that saint, he is supposed to have the power of walking on the waters.