what it chiefly depends on for its defence against an enemy, and this being but little available when the bird is flying. By taking the sky of the hostile birds, the swan, however, is enabled to perform its migratory flight in considerable safety, as the falcons are entirely harmless to any thing above them. The flight of the Hoopers when they are on their migrating journeys is much more rapid than from the size and weight of the birds one would be apt to suppose. As is the case with all birds of lofty flight, it does not appear to be so rapid as it really is. This is a point to which it is very essential to attend in all cases of birds, or indeed any thing else in motion. The portion of the retina which the visual impression of the observed object passes over is of course the standard which we have for the measure of its velocity. In consequence of this, its motion appears to be slower than it really is, in the same proportion that its distance is increased, so that a motion at five hundred yards requires to be ten times faster in order to have the same apparent speed as a motion at fifty yards distance. This renders it rather a difficult matter for an ordinary sportsman, however expert he may be in hitting partridges or other ground game when on the wing, to hit swans when they are passing over him in their migratory flight; and unless he takes aim before them, at a distance which experience only can determine, he is sure to miss. The wind, too, must be taken into calculation in order to insure a successful shot. The size and weight of the swans, with the abundance of their feathers, cause the wind to have a very great influence on the velocity of their flight. Hence they almost invariably go before the wind in their migrations, and wait, or even halt on their journey, if the wind be adverse. Before a stiff breeze they can make way at the rate of not less than one hundred miles in the hour, so that they are very soon out of the observer’s horizon; but against a wind of the same strength they can make very little way, and upon a strong cross wind they drift very far to leeward. In all ages these birds have enjoyed a considerable degree of fictitious interest, and, therefore, beside the exaggeration of the musical power of their “sweet voices,” there are various other improbable things alleged of them. For instance, it is said that when the frost begins to set in they assemble in multitudes and keep the water in a state of agitation to prevent it from freezing. The fact is, that all the agitation a flock of swans could produce in a lake would but make it freeze the more rapidly. It is probable, however, that they break the ice, when it is thin, and continue breaking it at the same place as fast as it freezes, as is the habit of very many animals in the winter season. * * * * * [Illustration: Drawn by Ch. Bodmer, Eng^{d} by Rawdon, Wright & Hatch FORT MACKENZIE.]