The Life and Times of Samuel Pierpont Langley

Time Stars Sun Spots and Flying Machines

by Tom Imerito

At the foot of the escalator on the first floor of Wesley Posvar Hall at the University of Pittsburgh a stately memento of the earliest days of aeronautics hangs from the ceiling in testament to the genius of its inventor, Samuel Pierpont Langley.  Dr. Langley came to Pittsburgh in 1867 to serve as director of the Allegheny Observatory and professor of physics and astronomy at the University.  Langley’s scientific intuition, practical resourcefulness and an unrelenting inclination to look at things with a fresh eye made him famous around the world.

When he arrived in Pittsburgh, Langley found the Allegheny Observatory to be inadequately equipped for research in fundamental astrophysics and completely lacking funds for either capital improvements or operations.  Determined, creative and indefatigable, Langley devised a service to sell the accurate time of day to railroads which depended on accurate timekeeping, a task complicated by the fact that each city and town in the United States operated on its own locally reckoned solar time.  Langley established the time each day, not by observing the Sun’s zenith, which varies considerably from place to place, day to day and season to season, but by the highly precise crossing of time stars as they passed a single strand of a spider’s web positioned within the field of a 4-inch transit telescope.  Langley transmitted his standardized time to subscribers via telegraph. The scheme was so successful that virtually all the railroads in the United States eventually subscribed, as well as many watchmakers. Langley solved the Allegheny Observatory’s financial problem by literally selling the time of day.

With the Observatory’s funding problem under control, Langley went on to conduct some of the earliest research in sun spot activity.  To do so, he invented a device to measure very small temperature differences in the solar spectrum, called a bolometer, a thin, electrically conductive strip of platinum or palladium whose electrical resistance changed in response to extremely small changes in temperature.  He ventured to Mount Whitney in the Sierra Nevada range to observe solar events with little atmospheric interference. As a consequence of his investigations, today one of Mount Whitney’s geologic siblings is named Mount Langley and the thermodynamic term Langley defines one thermo-chemical calorie per square centimeter.

Although his solar research is widely regarded as fundamental to the field of solar physics, Professor Langley’s appetite for innovation appears to have been insatiable.  Having been fascinated with bird flight since childhood, he went on to experiment with heavier-than-air flying machines.  On the lawn of the Allegheny Observatory he constructed a steam-driven whirling table, the arms of which rotated through a 200-foot arc at speeds of up to 70 miles per hour.  With this device he discovered that the faster an airfoil moved horizontally through the air, the less energy was needed to keep it aloft.

Langley took his findings to the Smithsonian, where he became Secretary of the Institution.  For years he conducted a series of flying-machine experiments with his “aerodrome,” the sixth iteration of which hangs in Posvar Hall.  He built a houseboat on the Potomac River, from which he launched his unmanned steam-driven, and later gasoline-powered, aerodrome.  For years his efforts met with failure.  Then on May 6, 1896, aerodrome number-five flew a half-mile at 80 to 100 feet above the Potomac River for 90 seconds.   Six months later, number five’s successor, (the one hanging in Posvar Hall) flew more than 5,000 feet.

Seven years later, in 1903, two attempts to fly a full-scale, manned aerodrome ended in failure.  Then, nine days after the second failed attempt, on December 17, 1903, the Wright Brothers made their history-making manned flight at Kitty Hawk.

Although Langley had not won the race to successful manned flight, the Wright Brothers are reputed to have openly acknowledged the encouragement they took from Langley’s efforts to achieve their common goal while serving in the prestigious position of Secretary of the Smithsonian Institution.

Today, in eponymous testament to Samuel Pierpont Langley’s contribution to science and technology stand a United Sates aircraft carrier, a mountain peak in the Sierra Nevada Range, a U.S. Air Force base, an international unit of temperature, and a University of Pittsburgh, building.

Not a bad flight.

© Copyright 2008, Thomas P. Imerito / dba Science Communications

This article first appeared in Tom Imerito’s TEQ column, Innovation Chronicles.