S. P. (Samuel Pierpont) Langley

Born in Roxbury, Massachusetts, in 1834, Samuel Pierpont Langley first trained in engineering and architecture before turning fully toward astronomy. He worked at several observatories and became director of the Allegheny Observatory in Pittsburgh, where he built a strong reputation through careful solar research and public scientific work.

Langley is especially remembered for inventing the bolometer, an instrument sensitive enough to detect very small changes in radiant heat. His studies of the Sun and the atmosphere helped make him one of the leading American scientists of his time, and in 1887 he became the third Secretary of the Smithsonian Institution.

Later in life, he devoted enormous energy to the problem of flight. His small experimental models achieved notable success, but his larger powered Aerodrome trials failed dramatically just before the Wright brothers' breakthrough. Even so, his work remains an important part of the story of early aviation, showing both the ambition and the difficulty of getting a flying machine off the ground.