Samuel Pierpont Langley (August 22, 1834 – February 27, 1906) was an American aviation pioneer, astronomer and physicist who invented the bolometer.

[5] In 1898, he received the Prix Jules Janssen, the highest award of the Société astronomique de France, the French astronomical society.

Langley arrived in Pittsburgh in 1867 to become the first director of the Allegheny Observatory, after the institution had fallen into hard times and been given to the Western University of Pennsylvania.

Through the friendship and aid of William Thaw Sr., a Pittsburgh industrial leader, Langley was able to improve the observatory equipment and build additional apparatuses.

In 1886, Langley received the inaugural Henry Draper Medal from the National Academy of Sciences for his contributions to solar physics.

[7] His publication in 1890 of infrared observations at the Allegheny Observatory in Pittsburgh together with Frank Washington Very along with the data he collected from his invention, the bolometer, was used by Svante Arrhenius to make the first calculations on the greenhouse effect.

In 1898, Langley received the Prix Jules Janssen, the highest award of the Société astronomique de France (the French astronomical society).

He built a rotating arm that functioned like a wind tunnel, and made larger flying models powered by miniature steam engines.

[10][11] The distance was ten times longer than any previous experiment with a heavier-than-air flying machine,[12] demonstrating that stability and sufficient lift could be achieved in such craft.

In 1898, based on the success of his models, Langley received a War Department grant of $50,000 and $20,000 from the Smithsonian to develop a piloted airplane, which he called an "Aerodrome" (coined from Greek words roughly translated as "air runner").

In contrast to the Wright brothers' design of a controllable airplane that could fly with assistance from a strong headwind and land on solid ground, Langley sought safety by practicing in calm air over the Potomac River.

The craft had no landing gear, the plan being to descend into the water after demonstrating flight which if successful would entail a partial, if not total, rebuilding of the machine.

On 28 May 1914, the Aerodrome was modified and flown a few hundred feet by Glenn Curtiss, as part of his attempt to fight the Wright brothers' patent, and as an effort by the Smithsonian to rescue Langley's aeronautical reputation.

Fred Howard, extensively documenting the controversy, wrote: "It was a lie pure and simple, but it bore the imprimatur of the venerable Smithsonian and over the years would find its way into magazines, history books, and encyclopedias, much to the annoyance of those familiar with the facts."

The Smithsonian's action triggered a decades-long feud with the surviving Wright brother, Orville, who objected to the Institution's claim of primacy for the Aerodrome.

So if the Aerodrome had flown stably, as the models did, Manly would have been in considerable danger when the machine descended, uncontrolled, for a landing—especially if it had wandered away from the river and over solid ground.

[20] Starting with his tenure at Allegheny Observatory in the Pittsburgh area in the late 1860s, Langley was a major player in the development of astronomically derived and regulated time distribution services in America through the later half of the 19th century.

Langley held himself responsible for the loss of funds after the June 1905 discovery that Smithsonian accountant William Karr was embezzling from the Institution.