Historical Markers
Rittenhouse Farm Historical Marker
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Rittenhouse Farm

Philadelphia and its Countryside/Lehigh Valley


Marker Location:
Germantown Pike (former US 422) 6 miles SE of Collegeville.

Dedication Date:
March 14, 1949

Behind the Marker

Oil on canvas of David Rittenhouse and his telescope.
David Rittenhouse, by Charles Willson Peale, 1796.
We have supposed Mr. Rittenhouse second to no astronomer living: that in genius he must be the first, because he is self-taught. As an artist he has exhibited as great a proof of mechanical genius as the world has ever produced. He has not indeed made a world; but he has by imitation approached nearer its Maker than any man who has lived from the creation to this day.

                                Thomas Jefferson, Notes on Virginia, 1784.

The recipient of Jefferson's accolades was David Rittenhouse, a quiet, shy, studious, and unassuming man, who was also the quintessential gentleman scientist. A self-taught genius, he was second to none when it came to astronomy.

As a lad, Rittenhouse wasn't much interested in working on the family farm and "he much preferred tinkering" to plowing.
Image of the complete Orrery.
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The Rittenhouse Orrery at the University of Pennsylvania Library, Philadelphia,...
Two uncles may have played a key role in his fascination with mechanical things: William Rittenhouse owned and operated his great- grandfather's paper mill (built in 1690, it was markerthe first paper mill in the colonies) and maternal uncle, David Williams, was a joiner. When Williams died in 1744, he left his nephew his books and toolbox and the boy started to tinker in earnest.

Soon, Rittenhouse built his own workshop and began to support himself by making and selling accurate and very finely crafted clocks. By 1770, he had attained acclaim not only for his timepieces but also for three detailed, working mechanical models of the solar system called orrerys.

For his work as a surveyor, Rittenhouse made his own compasses, chains, levels, telescopes, transits, and zenith sectors, which he used to perform surveys that fixed Pennsylvania's disputed borders and those of several other eastern states. His geographic knowledge and surveying skills enabled him to play leading roles in a number of projects to improve transportation between the western and eastern part of the state with canals and roads. In fact, in 1791 he was appointed by the legislature as one of the commissioners of the markerPhiladelphia and Lancaster Turnpike to direct the road survey and, once the turnpike was completed, he was named one of its managers.
Color image of telescope.
Astronomical transit telescope, made by David Rittenhouse, ca. 1769.

By his mid-twenties, Rittenhouse was also surveying the heavens with a homemade telescope. He was one of the first men to use spider threads as crosshairs to improve the accuracy of his telescopes and surveying instruments.

In June 1768 he and John Sellers were part of a team of Pennsylvanians that participated in the official British study the transit of Venus from the observatory he built on his family farm at Norriton. The accuracy of his work on the movement of Venus across the face of the sun brought Rittenhouse to the attention of the European scientific community. When he moved to 7th and Mulberry (later Arch) Sts. in Philadelphia in 1770, he built a new observatory and installed a "collimating" telescope - his own invention - to improve his observations of numerous celestial phenomena. Beginning in 1773, he made the astronomical calculations for a number of almanacs. He also recorded daily meteorological observations with barometers, thermometers, and a hygrometer, all of his own design.

Map of the Transit of Venus From Transactions of the American Philosophical Society Philadelphia, 1769.
David Rittenhouse's map of the transit of Venus, published in the first volume...
During the Revolutionary War, Rittenhouse provided valuable service to the nation, surveying and planning the defenses of Philadelphia and Pennsylvania; conducting experiments with telescopic sights for rifles and rifled cannon; and working to boost the production of bullets, guns, and saltpeter. Elected a delegate to draft Pennsylvania's state constitution in 1776, he also served as state treasurer from 1777 to 1789. After the formation of the new federal government, President George Washington appointed him the first director of the U.S. Mint in 1792. For three years Rittenhouse applied his mathematical, mechanical, and scientific skills to the manufacture of the nation's coinage.
Watercolor corner scene of home.
David Rittenhouse's home at 7th and Mulberry Streets, Philadelphia, PA, by C....

Although Rittenhouse never had more than a few years of formal schooling, he read widely and immersed himself in scientific works from Europe. As he scientific reputation grew, Rittenhouse became involved in a growing array of the projects that were cementing Philadelphia's reputation as the scientific capital of the new nation. He conducted experiments on the compressibility of water, on the impact of heat on metal and wood, and on magnetism. He designed eyeglasses for Washington, and made improvements on the Franklin stove. He received numerous honors, including honorary degrees from the College of Philadelphia, the College of New Jersey, and the College of William and Mary. Elected to membership in the American Philosophical Society in 1768, he later served in a variety of offices within the organization including president from 1791 until his death in 1796. In 1782, he was chosen to be a fellow of the American Academy of Arts and Sciences in Boston, and in 1795 he was selected to be a fellow of the Royal Society in London.

Shy throughout his life, Rittenhouse made few close friends. His few intimates, however, included some of the greatest scientific minds of the day. After markerBenjamin Franklin's return from France in 1785, Rittenhouse became one of his closest friends and regularly attended his Wednesday night philosophical parties." He was one of the pallbearers at Franklin's funeral and in his will, Franklin left him his telescope.

After Philadelphia became the capital of the new nation in 1790, Secretary of State Thomas Jefferson was a frequent visitor to the Rittenhouse home. He advised Jefferson on the Virginian's proposed plan for a new, decimal-based system of weights, measures, and coinage for the US in 1790, which Congress ignored. (Today the United States has yet to adopt the metric system common throughout the rest of the world.) After markerDr. Joseph Priestley moved to Pennsylvania in 1794, the two admirers visited on occasion to discuss scientific, political, and religious matters.

After a lifetime of work that made science practical and brought the benefits of the science to humankind, David Rittenhouse died at his home in Philadelphia on June 26, 1796. On the evening of the following day he was buried underneath the floor of his observatory.
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