The present work is in reality the outcome of what was first undertaken as a holiday recreation in the summer of 1903. While engaged upon a research of quite a different character, I reread, with greater care, Audubon's Ornithological Biography, and after turning the leaves of his extraordinary illustrations, it seemed to me most strange that but little should be known of the making of so original and masterful a character. As I was in England at the time some investigations were undertaken in London, but, as might have been expected, with rather barren results. After my return to America in the following year the search was continued, but as it proved equally fruitless here, the subject was set aside. Not until 1913, when this investigation was resumed in France, did I meet with success.