"The wing, both when at rest and when in motion," Pettigrew declared, "may not inaptly be compared to the blade of an ordinary screw propeller as employed in navigation. Thus the general outline of the wing corresponds closely with the outline of the propeller, and the track described by the wing in space IS TWISTED UPON ITSELF propeller fashion." Numerous attempts to apply the newly discovered principles to artificial birds failed, yet came so close to success that they fed instead of killing the hope that a solution of the problem would one day ere long be reached. "Nature has solved it, and why not man?" From his boyhood days Samuel Pierpont Langley, so he tells us, had asked himself that question, which he was later to answer. Langley, born in Roxbury, Massachusetts, in 1834, was another link in the chain of distinguished inventors who first saw the light of day in Puritan New England. And, like many of those other inventors, he numbered among his ancestors for generations two types of men--on the one hand, a line of skilled artisans and mechanics; on the other, the most intellectual men of their time such as clergymen and schoolmasters, one of them being Increase Mather. We see in Langley, as in some of his brother New England inventors, the later flowering of the Puritan ideal stripped of its husk of superstition and harshness--a high sense of duty and of integrity, an intense conviction that the reason for a man's life here is that he may give service, a reserved deportment which did not mask from discerning eyes the man's gentle qualities of heart and his keen love of beauty in art and Nature. Langley first chose as his profession civil engineering and architecture and the years between 1857 and 1864 were chiefly spent in prosecuting these callings in St. Louis and Chicago. Then he abandoned them; for the bent of his mind was definitely towards scientific inquiry. In 1867 he was appointed director of the Allegheny Observatory at Pittsburgh. Here he remained until 1887, when, having made for himself a world-wide reputation as an astronomer, he became Secretary of the Smithsonian Institution at Washington. It was about this time that he began his experiments in "aerodynamics." But the problem of flight had long been a subject of interested speculation with him. Ten years later he wrote: