=Flight.= The habit of flying is objectionable in domestic birds because it makes them more difficult to control. It has no direct use except in pigeons kept for flying. There is, however, a very important connection between development for flying and the value of birds for the table. The muscles of the wings furnish the greater part of the edible meat of most birds. The most desirable birds for food purposes are those which have the wing muscles well developed, yet not quite strong enough to enable them to fly easily. In such birds the breast meat remains comparatively soft through life, while in birds that fly well it becomes hard in a very short time. That is why the breast meat of the pigeon is relatively tougher in an old bird than the breast meat of a fowl or turkey. The balance between capacity for flight and neglect to use it, which is desired in birds grown for the table, is secured by giving them opportunity to exercise their wings moderately but not for progressive practice in flying, which would soon enable them to fly easily over the fences used to confine them. To regulate such exercise the perches for birds that roost are made low, or in an ascending series in which each perch after the first is reached from the one below it, while fences are made so much higher than the distance the bird is accustomed to fly that the failures of its first efforts to go over them discourage it. Ducks and geese, which do not roost, flap their wings a great deal, and if they have room often exercise them by half running and half flying along the ground. =Mechanism of the wing.= In its structure and in the muscular power that moves it, the wing of a bird is a wonderful piece of mechanism. A bird in flying strikes the air with its wings so rapidly that the movements cannot be accurately counted. The heron, which is a slow-flying bird, makes from one hundred twenty to one hundred fifty downward strokes of its wings a minute. As each downward stroke must be preceded by an upward stroke, this means that the wings make from two hundred forty to three hundred separate movements a minute. In such swift-flying birds as the pigeon the movements of the wings can be distinguished but cannot be counted. The fastest movements of the wings are not made by the swiftest fliers. In order to fly at all some land birds with comparatively small wings have to move them so fast that the movements make a blur and a whirring noise. The partridge is an illustration of a bird of this class.