13 AUGUST 1927, Page 12

Air currents explain a great many of the accomplishments of

birds, as airmen discovered as soon as they could fly. Wilbur Wright himself told me that he had studied bird.4' flight for interminable hours spread over many years, but discovered almost nothing. It was only when flight was accomplished that he and others appreciated the birds' continuous subtle use of the movements of the air, especially the more vertical currents. He himself had a surprising theory about the buzzards, which are as successful as the bigger gulls in moving upwards or parallel with the earth without any apparent beating of the wing. He believed that they created or at least encouraged an up-draught by flying round and round—as their wont is—in an ascending spiral 'I