Mr. Wright was so impressed by this practice among birds
that he advanced his theory beyond the probable. He thinks, or at one time thought, that the buzzards have learnt a
mechanical device for creating, or at any rate increasing and establishing, such upward currents. By circular revolutions they set the air moving in their wake, as one can set the wa,..e circulating in a basin, and on this they are carried without' further effort on their own part. It all sounds a little like an excursion into the fallacy of perpetual motion, but there may be a partial truth in it. I fancied in Washington that the buzzards revolved especially above the circular open spaces in this city of concentric streets. The wind rushing along the streets perforce rose as it reached the circle ; and on this rising column spirally twisted by the revolving wings the buzzards enjoyed their daylong hovering. The best spectacle of the use of such upward winds that ever I have seen was at Miirren in Switzerland, where the crows and choughs sweep up the valleys at quite astounding speed and with obvious gusto, though they do not move a wing. A city after all is a place of cliffs and valleys that will bear comparison—especially in America—with the very Alps.
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