eathers, which by the action of two screws of quill feathers, rotating
in opposite directions, would rise to the ceiling; and the full
revelation of the structure and action of bird wings set forth by
Pettigrew in 1867.

"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