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134 wing, I think, is considerably smaller in proportion to the body than is that of the wild duck. When I see these birds going along over the sea at the rate they do, it does not seem to me impossible that a man should fly, if only his arms were to sprout feathers and his pectoral muscles enlarge sufficiently to enable him to move them with the same quickness. Is there, by the by, any special adaptation to the power of flight in the body and bones of a bat? We are generally referred to such arrangements in reference to the flight of birds, with a view to lessening the wonder of it, as if birds were the only things that flew. Bats, however, are mammals like ourselves, and their aerial performances are very wonderful. I have often watched them and the swifts together, at the close of a summer day, and have been hardly able to decide which of the two showed the greater mastery over the element in which both moved. The swifts indeed alone skimmed on outspread wings, without pulsating them; but in quick, sudden turns in every direction, in the power of instantaneously and abruptly changing the angle of their flight, and especially in descending, sometimes almost perpendicularly, the bats excelled them. In regard to speed, the disparity did not appear to be so great as I suppose it must have been. I do not know if any observations have been made to determine the speed at which bats fly, but they often seem to go very fast.

To return to the puffins, their powers of flight extend a little beyond mere speed gained by constant