MESSRS. EDITORS—In view of the many aerial projects which are proposed, I beg leave to offer the following suggestion : I propose that some ot our enterprising naturalists examine .into the relation, existing between tbe -weight and the volant strength of birds. By the volant strength of birds I mean, oi course, that part of their power which is applied exclusively to their aerial propulsion. The proportion between this strength, and their weight, has never been ascertained, at least to my knowledge. Let this ratio be determined and we shall be in possession of an important, and, indeed, almost indispensable premise on which to base our reasonings in respect to aerial navigation. There is surely enough of mechanical science in the land to calculate, before-hand, the weight and power of any proposed flying ship, and to bring them to this test provided by nature. It is evident to every one that if the ratio between the power and weight, of any machine, is less than the ratio between the power and weight of birds, such a machine must inevitably fail to sustain itself in the air; and that there can be no hope of success, unless this ratio is as great, or greater, in the one case than in the other. And it seems to me that a due apprehension of this fact, would put an end to so many baseless projects of aerial navigation, that we so frequently meet with now-a-days. Cannot some of our scientific friends, favor us with their views on this subject. A SUBSCRIBER. [The above is a good suggestion; but to it we must necessarily add another, viz., the means of sustaining that power—the relation between the lood which sustains the force of the fowl and that of a machine.—Ed.