RITTENHOUSE, William, paper-maker, born in the principality of Broich, Holland, in 1644; died in Roxborough, Philadelphia, Pennsylvania, in 1708. He was a Mennonite preacher, and with his sons, Claus and Gerhard, and his daughter, Elizabeth, came to this country from Amsterdam, Holland, and settled at Germantown, Pennsylvania, in 1687-'8. His ancestors for many generations had been paper-makers in Arnheim, and he built in 1690 the first paper-mill in this country, on Paper-mill run, a branch of Wissahickon creek, in Roxborough township. The mill was owned by a company, among whom were, besides himself, Robert Turner, Thomas Tresse, Samuel Carpenter, and William Bradford, the first printer in the British colonies south of New England. In 1700-'1 this mill was carried away by a freshet, but, with the aid of William Penn, was rebuilt of stone in 1702. Rittenhouse became the sole owner of the paper-mill in 1704, and before his death gave it to his son, Claus or Nicholas (1666-1784). The business increased, and soon an additional mill of stone was added. From paper that was made at this place William Bradford was supplied, and Gabriel Thomas writes: "All sorts of very good paper are made in the German Town." The business was carried on by direct descendants of William at the same place until well into the 19th century. William continued his preaching in this country, being the first Mennonite minister in Pennsylvania, and he and his son were granted naturalization papers by Thomas Lloyd, the deputy governor, on 7 May, 1691. --Among Claus's children was MATTHIAS (1708--1779), who became a farmer and settled in Norriton township, Montgomery County, Pennsylvania, and the latter's eldest son was David, astronomer, born in Roy borough, Pennsylvania, 8 April, 1732: died in Philadelphia, 26 June, 1796. He was early trained to work on a farm, but an uncle, dying when the boy was about twelve years old, left him a chest of tools, together with a few books that contained the elements of arithmetic and geometry, and some mathematical calculations. These seem to have determined the bent of his life, for he covered the handle of his plough, and even the fences around the fields, with mathematical calculations. He was not without considerable mechanical ability, as he had made a complete water-mill in miniature when he was eight years old, and at seventeen he made a wooden clock, and later one in metal. In 1751 he persuaded his father to advance money with which he purchased in Philadelphia an outfit of tools, and then established himself in Norriton as a clock- and mathematical-instrument-maker. His (lays were spent in following his trade, and his nights were given to study, tie solved abstruse Mathematical and astronomical problems, discovering for himself the method of fluxions, and for a long time believing that he was its originator, he mastered an English translation of Newton's "Principia," also devoting himself to the study of optics. In 1751 he became acquainted with Thomas Barton (q. v.), who supplied him with books, from which he gained a knowledge of Latin and Greek. His clocks became celebrated for their accuracy : he obtained a local reputation for astronomical knowledge, and through Mr. Barton, who became his brother-in-law, he was introduced to men of learning. In 1763 he was called on to determine the initial and most difficult part of the boundary-line between Pennsylvania and Maryland, and this task was so well accomplished that he was offered extra compensation on its completion. Although the instruments were of his own manufacture, when the official astronomers, Charles Mason and Jonathan Dixon, arrived in 1763, they accepted his observations without change. He was appointed in 1769, at the request of a commission that was selected by New York and New Jersey, to settle the boundary-lines between these colonies. Meanwhile he continued his scientific researches, studied the variations in the oscillations of the pendulum that are caused by the expansion and contraction of the material from which it was made, and devised a satisfactory plan of compensation ; also about this time he made a thermometer on the principle of the expansion and contraction of metals. Later he constructed an orrery on a new and more perfect plan than had ever before been attempted, which, when it was finished in 1770, was regarded by John Adams as "a most beautiful machine .... It exhibits almost every motion in the astronomical world." Princeton purchased it for £300, and later Rittenhonse made a larger instrument from the same model for the University of Pennsylvania, for which he received £400. In January, 1768, he was elected a member of the American philosophical society, and in June of that year he addressed the society on the transit of Venus that occurred on 3 June, 1769, in consequence of which three committees were appointed by that body to make observations. One of these, under Rittenhouse, was stationed at his observatory in Norriton, and all of the preliminary arrangements were left to him. He set to work with great zeal; Thomas Penn sent a reflector from Europe, and other apparatus was secured, all of which Rittenhouse mounted. The observations, according to the testimony of the astronomer royal of England, were excellent, and, according to another authority, " the first approximately accurate results in the measurement of the spheres were given to the world, not by the schooled and salaried astronomers who watched from the magnificent royal observatories of Europe, but by unpaid amateurs and devotees to science in the youthful province of Pennsylvania." In 1769 he observed the transit of Mercury, and a year later he calculated the elements of the motion and the orbit of a comet. In 1770 he removed to Philadelphia, where he continued to engage in mechanical pursuits, and also for some years had charge of the state-house clock. He continued his experiments, and in 1771 investigated the electrical properties of the gymnotus, or electric eel. In 1772 he was engaged to survey and ascertain the levels of the lands between the Susquehanna and Delaware rivers, and in 1773 he was chief of a commission to make the Schuylkill river navigable. He was commissioner from Pennsylvania in 1774 to determine the northwestern extremity of the boundary between New York and Pennsylvania. In March, 1775, the American philosophical society presented for the consideration of the Pennsylvania assembly a plan for the erection of an observatory under state control, with a view of tendering the appointment of director to Mr. Rittenhouse. The Revolutionary war prevented the carrying out of this project, and he was ordered "to prepare moulds for the casting of clock-weights, and send them to some iron-furnace, and order a sufficient number to be immediately made for the purpose of exchanging them with the inhabitants of this city for their leaden clock-weights." In October, 1775, he was appointed engineer to the committee of safety, and in that capacity he was called upon to arrange for casting cannon of iron and brass, to view a site for the erection of a Continental powder-mill, to conduct experiments for rifling cannon and musket-balls, to fix upon a method of fastening the chain for the protection of the river, to superintend the manufacture of saltpetre, and to locate a magazine for military stores on Wissahickon creek. He was appointed one of the committee of safety in April, 1776, its vice-president in August, and in November the proclamations that were issued bore his name as presiding officer. In March, 1776, he was elected a member of the assembly from Philadelphia, and later he became a member of the convention that met on 15 July, 1776, and drafted the first constitution for the state of Pennsylvania. He was one of the board of war for the state of Pennsylvania, and later one of the council of safety, to whom the most absolute powers were temporarily granted. In January, 1777, he was elected first state treasurer under the new constitution, and he was unanimously elected to the same office for twelve years, until finally, in 1789, he declined to serve any longer. On several occasions he was appointed to act on various boundary commissions, and in 1792 he was appointed first director of the mint, which place he filled for three years. From 1779 till 1782 he was professor of astronomy in the University of Pennsylvania, and also a trustee and vice-provost of the same institution. In 1772 he received the honorary degree of A. M. from Princeton, and in 1789 the same college conferred on him the degree of LL.D. He was elected a fellow of the American academy of arts and sciences in 1782, and in 1795 he was chosen an honorary fellow of the Royal society of London. In 1771 he was elected one of the secretaries of the American philosophical society, of which he became vice-president in 1786, and, on the death of Benjamin Franklin in 1790, he was chosen its president, which office he then held until his death. The early volumes of the transactions of that society were enriched by his scientific contributions, about twenty in number; his most elaborate paper, " An Oration on Astronomy" (Philadelphia, 1775), was delivered on 24 February, 1775. Thomas Jefferson, who succeeded him as president of the Philosophical society, wrote" "' We have supposed Mr. Rittenhouse second to no astronomer living; that in genius he must be first, because he is self-taught." See "Life of David Rittenhouse," by James Renwick, in Sparks's "American Biography" (Boston, 1834), and " Memoirs of the Life of David Rittenhouse," by William Barton (Philadelphia, 1813). RITTER, Abraham, author, born in Philadelphia in September, 1792; died there, 8 October, 1860. His father, , Jacob, was a soldier in the Revolutionary war', and the son became a merchant in his native city. He was for fifty years a member of the board of elders of the Moravian church, tie published a " History of the Moravian Church in Philadelphia, 1742-'57" (Philadelphia, 1857), and "Philadelphia and her Merchants " (1860).