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Samuel P LangleySamuel P. Langley

creator of time zones and builder of a steam-powered airplane

Samuel Pierpont Langley was born in Roxbury, Massachusetts, on August 22, 1834, the son of Samuel, a merchant, and Mary (Williams) Langley. He was educated at the Boston Latin School and was reading books on astronomy by the age of nine. His brother John helped him build astronomical instruments, including refracting telescopes, and together they observed the phases of Venus, craters and "seas" on the moon, the Galilean moons of Jupiter, and the rings of Saturn.

Langley began his education at Boston Latin School and completed it at English High School of Boston, from which he graduated in 1851. Unable to find work as an astronomer, he decided to pursue a career in architecture and apprenticed with architects and designers in St. Louis and Chicago to develop skills in mechanical and free-hand drawing. This profession failed to stimulate him, however, so he returned to Massachusetts and went back to making telescopes. His career as an astronomer began in 1865, when he was hired as an assistant at the Harvard College Observatory. He spent about a year at Harvard before being hired by the U.S. Naval Academy. Officially hired as a professor of mathematics, his actual job was to restore the operation of the Academy's small observatory. In 1867 he became director of the Allegheny Observatory and professor of astronomy at Western University of Pennsylvania (now the University of Pittsburgh), positions he held until 1891.

Allegheny Observatory

Langley arrived at an Observatory that was in serious disarray -- most of its equipment was broken, the building needed repair, and it didn't have a library. Thanks to his fund-raising efforts, both the Observatory and the astronomy department got the funding they needed to buy and build instruments, which were then used to help both institutions raise even more funds. One of the first new instruments acquired by the Observatory was a small transit telescope used to observe the position of the stars as they cross the celestial meridian.


In the mid-1860's, there was no such thing as "standard time," every town's clocks were set according to the Sun's position at midday and very few of those clocks were accurate. Such "timekeeping" had worked well for centuries, but the need for greater accuracy grew as railroads laid more and more tracks. Trains ran by a published schedule, but the scheduling was chaotic. If the watches of an engineer and a switch operator differed by even a minute or two, it could mean disaster; two trains could be on the same track at the same time and crash. Langley took this situation as an opportunity for the Allegheny Observatory to help.

Using astronomical observations obtained from the Observatory's new transit telescope, Langley devised a precise time standard, including time zones, that became known as the Allegheny Time System. He then published a pamphlet suggesting that the Observatory could establish the correct time and telegraph this information at intervals to railroad stations. The Pennsylvania Railroad signed up and Langley began to transmit the correct time twice per day to the railroad's several hundred stations. This arrangement proved so successful that soon all sorts of businesses signed up, thus bringing financial support to the Observatory. Revenues from the Allegheny Time System continued to fund the Observatory until the U.S. Naval Observatory began providing the signals for free in 1883.

Solar Research

As an astronomer, Langley spent many years observing the sun. He attempted to use photography to document his observations but this proved unsatisfactory at the time so he had to rely on his training in drawing to produce hundreds of drawings of solar phenomena, many of which were the first the world had seen. As his work accumulated information, he believed that this information should be made available to the public and made a habit of writing articles for "lay" readers and giving public lectures. His interest in the solar constant (solar energy reaching the earth) led him to build instruments called calorimeters to measure how much energy the sun was radiating, as well as bolometers to make similar measurements on stars.

Smithsonian Institution

Langley became Assistant Secretary of the Smithsonian Institution in January of 1887, and succeeded Spencer Fullerton Bailey as Secretary in November of that same year. As Secretary, Langley established the Smithsonian Astrophysical Observatory and developed a research program in astrophysics. The National Zoological Park and the National Museum of Natural History were both established during his tenure, and Langley was instrumental in getting the Smithsonian designated as the "National Art Gallery."


Langley began experimenting with aerodynamics while at Allegheny Observatory, using a large whirling table he designed and built himself as a test platform. He continued his work after moving to the Smithsonian, where he used his table to test a variety of stuffed birds (including a frigate bird, a California condor, and an albatross), but was never able to get one to fly. He also built over 100 rubber band-powered "aerodromes," eventually achieving flights lasting 6 to 8 seconds and covering 80 to 100 feet.

Having achieved flight with models launched from his rotating table, Langley next began experimenting with aerodromes powered by steam. "Aerodrome No. 0,' built in 1891, failed, as did Aerodromes 1 and 2. By the time he tested Aerodrome No. 3 in 1892, Langley had made a stronger frame and developed a better method of creating the steam. Although this test also failed, it provided enough data for him to incorporate even more improvements into Aerodrome No. 4, which he launched from a "catapult contraption" atop a houseboat on the Potomac River. After a series of more failures, Aerodrom No.4 finally managed to hop about 130 feet over the river in October 1894. Aerodrome No.5 "flew" about 100 feet in December of that same year, and Langley was ready to attempt true "heavier-than-air" powered flight.

Aerodrome No 5 in flight, May 6, 1896Langley finally achieved success on May 6, 1896, when his Aerodrome No. 5 made two powered flights, of 3,300 and 2,300 feet, at maximum altitudes of 80 and 100 feet, and at speeds of 20 to 25 miles per hour. Aerodrome No. 6 flew nearly a mile on November 11, and 4,200 feet at about 30 mph on November 28. This unmanned tandem-wing craft employed a lightweight steam engine for propulsion. The wings were set at a distinct dihedral angle so that the craft was dynamically stable, capable of righting itself when disturbed by a sideways breeze. There was no method of steering this craft, however, nor would it have been easy to add any means to control the direction the craft flew. Having achieved his primary goal, Langley wrote an article about his work for McClure's magazine in June of 1897, and then resumed his work as Secretary of the Smithsonian Institution.

In December 1898, Langley agreed to construct an Aerodrome capable of carrying a human operator for the U.S. Army Board of Ordnance and Fortification. Although he originally agreed to do the work for free and in his own time, he ultimately requested and received $50,000 from the Army and another $20,000 from the Smithsonian to cover his costs.

Before moving directly to human-controlled aircraft, Langley built the "Quarter-Size Aerodrome" to test the basic design and various components. This machine made flights of only 150 and 300 feet in June of 1900, but by August of 1903 it had made a flight of 1,000 feet. He was now ready to test the "Langley Large Aerodrome A," which was powered by a gasoline engine modified by engineer and test pilot Charles Manley.

Photograph of first attempt to fly the manned Langley Aerodrome, October 7, 1903The Large Aerodrome made its first attempt at flight in October of 1903. It proved to be nose-heavy, however, and plunged into the Potomac River almost immediately after being launched. After repairing the heavily-damaged craft, another test was conducted on December 8. This time the Aerodrome went into the Potomac tail-first and was almost completely destroyed. Manley managed to escape both failures without injury, but Langley decided enough was enough and decided to end his aviation experiments.

Samuel P. Langley died of a stroke in Aiken, South Carolina, on February 2, 1906, and was buried in Forest Hill Cemetery, Boston. Despite his failure to achieve controlled flight with his Aerodromes, he is the namesake of Langley Air Force Base and NASA's Langley Research Center.

Flying Machines
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This page was last updated on December 19, 2014.

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