Rittenhouse, David

Rittenhouse, David,

1732–96, American astronomer and instrument maker, b. near Germantown, Pa., self-educated. A clockmaker by trade, he developed great skill in the making of mathematical instruments. He was called upon to determine, with his own instruments, the boundary lines of several states and also part of the boundary known as the Mason-Dixon LineMason-Dixon Line,
boundary between Pennsylvania and Maryland (running between lat. 39°43'26.3"N and lat. 39°43'17.6"N), surveyed by the English team of Charles Mason, a mathematician and astronomer, and Jeremiah Dixon, a mathematician and land surveyor, between 1763 and
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. In 1769 he was asked by the American Philosophical Society to observe the transit of Venus. His contributions include the use of measured grating intervals and spider threads on the focus of the telescope. Active in public affairs, he was a member of the convention that framed Pennsylvania's constitution and was state treasurer (1777–89) and director of the U.S. mint (1792–95). After the Revolution he was an Anti-Federalist. He succeeded Benjamin Franklin as president (1791–96) of the American Philosophical Society; most of his writings appeared in its Transactions.


See biography by B. Hindle (1964).

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Rittenhouse, David

(1732–92) instrument maker, inventor, astronomer; born in Paper Mill Run, Pa. Largely self-taught, he was a mathematical prodigy and showed a talent for mechanics; by the age of 19 he was an innovative clockmaker; during his early twenties he was making telescopes; he is credited with being the first to introduce the use of cross hairs (spider web) in transit telescopes. Using his own instruments, he became a student of astronomy and would make several important contributions including a calculator of the sun's parallax. As a surveyor, he was responsible for establishing the basis of what became the Mason and Dixon line demarking Pennsylvania from Maryland; this led to his employment as a surveyor to settle boundary disputes. About 1770, when he moved to Philadelphia, he constructed two orreries that displayed planetary motions. (One survives at the Franklin Institute in Philadelphia.) He continued to work at and publish a variety of scientific and mathematical problems. During the American Revolution he served with the Philadelphia Committee of Safety, and oversaw the manufacture of arms and munitions. A member of the convention that produced Pennsylvania's constitution (1776), he was state treasurer (1777–89), a teacher of astronomy at the University of Pennsylvania (1777–89), a commissioner who set up the First Bank of the United States (1791), and first director of the U.S. Mint (1792–95). In 1791 he succeeded Benjamin Franklin as president of the American Philosophical Society and in 1795 he was elected a fellow of the Royal Society. At his death he was regarded as the foremost American scientist/mathematician of the day.
The Cambridge Dictionary of American Biography, by John S. Bowman. Copyright © Cambridge University Press 1995. Reproduced with permission.