Popular Science Monthly/Volume 36/April 1890/Sketch of David Rittenhouse

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David Rittenhouse.


"AS a citizen of Pennsylvania" says William Barton, in the preface to his "Memoirs of the Life of David Rittenhouse"; "as an inestimable public and private character; as a distinguished son of science, of great probity and extensive usefulness in society—in all these points of view, the history of Dr. Rittenhouse may be contemplated as holding a relationship with almost every object connected with science and art in his day that could in any way contribute to the well-being of mankind in general and his native country in particular." He, in fact, acquired a fame in the period of the infancy of American science, the nature and extent of which can hardly be realised in this day; and his gifts, then regarded as extraordinary, were always freely placed at the service of the public.

David Rittenhouse was born in Roxborough Township, near Germantown, Pa., April 8, 1732, and died in Philadelphia, June 26, 1796. He was descended from a family of paper-makers residing at Arnheim, Guelderland. His great-grandfather, William Rittenhouse, a Mennonite preacher, came from Holland with his family in 1687-'88; was the first Mennonite minister in Pennsylvania; and established the first paper-mill in this country, at the spot where David was born.

David was early put to work on the farm, and was plowing at fourteen years of age. An uncle dying had left him a chest of tools and a few books on arithmetic and geometry, with some manuscript mathematical calculations. These furnished palatable food to his mind, and his biographers tell of his having covered the handle of his plow and the fences around the field with his workings of the problems which they set before him. As the uncle mentioned above was his mother's brother, it is inferred that he inherited his genius from his mother's side. His mechanical talent was shown in his construction of a complete water-wheel in miniature when eight years old, a wooden clock when seventeen, and a clock with metallic works at a later age. His father was not disposed at first to favor the youth's tastes, but eventually he furnished him with money enough to buy a set of clock-making tools; and David built a workshop at Norriton, whither the family had removed, where he carried on the clock-making business for several years. He at the same time pursued his studies so diligently that he impaired his constitution, and contracted a pain that afflicted him all his life. Astronomy appeared to be his favorite study; and he was interested in optics and mechanical science. He discovered himself, independently, the method of fluxions, of which, in his imperfect knowledge of what Newton and Leibnitz had done, he believed himself to be the originator; and mastered the English translation by Motte of Newton's "Principia."

The acquaintance which he formed in 1751 with Thomas Barton, who afterward married his sister, had an important influence in shaping his career. Rittenhouse, according to William Barton, "possessed a sublime native genius; which, however, was yet but very imperfectly cultivated for want of indispensable means of extending the bounds of natural knowledge." Barton had enjoyed these means, and had acquired the reputation of being a man of learning. He found Rittenhouse's society profitable, and Rittenhouse found his equally so. Barton aided Rittenhouse greatly by helping him to the books he needed. Partly through his instrumentality a circulating library was established at Norriton; and he bought books for Rittenhouse when he went to Europe.

Mr. Rittenhouse was called upon in 1763 to determine the initial of the boundary-line between Pennsylvania and Maryland, his particular duty being defined to be to ascertain and fix the "circle to be drawn at twelve miles' distance from New Castle, northward and westward, with the beginning of the fortieth degree of north latitude," etc. The work was an arduous one, and involved going through a number of tedious and intricate calculations. It was performed in a satisfactory manner, for which acknowledgment was made in the shape of extra compensation, and with instruments to a large extent of Rittenhouse's own making; and his observations were accepted without change by the official astronomers, Mason and Dixon, when they took charge of the work. He was afterward appointed to a similar work in 1769, by the commission to settle the boundary between New York and Pennsylvania. Among his scientific studies at this period were the investigation of variations in the oscillations of the pendulum under changes of temperature, with the device of a plan for compensation, and the construction of what he called a metalline thermometer. This instrument was so made—on the principle of the expansion and contraction of metals under variations of temperature—that the degrees of heat and cold were indicated by the movements of an index moving along a graduated semicircle. It was adapted, in form and size, to be carried in the pocket. He discussed the compressibility of water in the light of an experiment that had been reported to the Royal Society, and observed, in a letter to Mr. Barton, that, although the experiment did not please him, he did not doubt the fact; for, "if the particles of water were in actual contact, it would be difficult to conceive how any body could much exceed it in specific gravity; yet we find that gold does, more than eighteen times." We find him also at this time (1767) indulging in some amusing speculations on the possibility of a man's moving the world. Some one having published the result of calculations he had made respecting the fulfillment of Archimedes's famous dictum on the subject, Mr. Rittenhouse gave the result of his own computations, which was that "the force wherewith a man acts when he lifts a weight of two hundred pounds, if applied without intermission for the space of one hundred and five years, is sufficient, without any machinery, to move the earth one inch in that time; and it must, from the velocity received by that force alone, continue forever after to move at the rate of one inch in fifty years." The first calculator had computed that twenty-seven billions of years would be required to accomplish the movement.

Mr. Rittenhouse's reputation as an astronomer became conspicuous, and his name, according to Mr. Barton, acquired a celebrity even in the Old World, "of which his early but now much-increased fame in his native country was a sure presage." A great bound was given to his fame by his construction of an orrery, or apparatus for illustrating the planetary motions, and by the conspicuous part which he took in the observations of the transit of Venus of 1769.

The design of the orrery is indicated in the correspondence with Mr. Barton in 1767, in the course of which Mr. Rittenhouse says: "I did not design a machine which should give the ignorant in astronomy a just view of the solar system; but would rather astonish the skillful and curious examiner by a most accurate correspondence between the situations and motions of our little representatives of the heavenly bodies and the situations and motions of those bodies themselves. I would have my orrery really useful by making it capable of informing us truly of astronomical phenomena for any particular point of time, which I do not find that any orrery yet made can do."

This instrument was bought before it was finished for Princeton College. The trustees of the College of Philadelphia had also been bargaining for it, and were disappointed over the turn the affair had taken. Mr. Rittenhouse had made a saving clause in his bargain in favor of the College of Philadelphia, in agreement with which he began another orrery for that institution. "This," he said, "I am not sorry for, since the making of the second will be but an amusement compared with the first; and who knows but that the rest of the colonies may catch the contagion? "The sum of two hundred pounds was obtained toward paying for the instrument by means of lectures on astronomy delivered by Rittenhouse's friend, the Rev. Dr. Smith, Provost of the College of Philadelphia, concerning which the Rev. Dr. Peters wrote," The doctor in his introductory lecture was honored with the principal men of all denominations, who swallowed every word he said with the pleasure that attends the eating of the choicest viands, and in the close, when he came to mention the orrery, he overexcelled his very self." The members of the Assembly of Pennsylvania took a view of the orrery, and, "being of the opinion that it greatly exceeds all others hitherto constructed, in demonstrating the true Situations of the celestial Bodies, their Magnitudes, Motions, Distances, Periods, Eclipses, and Order, upon the principles of the Newtonian System," voted the constructor three hundred pounds in consideration of his mathematical genius and mechanical abilities, and appointed a committee to agree with him for a new orrery for the use of the public. This purpose was not carried out. Mr. Rittenhouse became engaged in public enterprises, which occupied his time till the beginning of the Revolution, when all other interests were suspended.

The praises which were bestowed upon Mr. Rittenhouse for his orrery were extravagant, and seem now even absurd; but nothing, perhaps, can more clearly illustrate the infantine condition of American science at the time.

Mr. Barton, by way of emphasizing the assertion that the skill and accuracy he displayed in the construction of his mathematical and astronomical instruments were not surpassed by similar works of the most celebrated British mathematicians, remarks that "his profoundness in astronomical science and his wonderful ingenuity, manifested in the construction of his orrery, leave him without a rival in the twofold character of an astronomer and mechanic." Dr. Jedediah Morse, in his "Geography" (1789), noticing some of the more prominent productions of scientific ingenuity and skill in America, observed that "every combination of machinery may be expected from a country, a native son of which, reaching this inestimable object in its highest point, has epitomized the motions of the spheres that roll throughout the universe." Mr. Thomas Penn, of London, was surprised that the instrument could have been executed in Pennsylvania. Joel Barlow wrote, in the "Vision of Columbus":

See the sage Rittenhouse, with ardent eye,
Lift the long tube and pierce the starry sky;
Clear in his view the circling systems roll,
And broader splendors gild the central pole;
He marks what laws th' eccentric wand'rers bind,
Copies Creation in his forming mind,
And bids beneath his hand in semblance rise,
With mimic orbs, the labors of the skies.

Thomas Jefferson, the sober statesman, Mr. Rittenhouse's successor as President of the American Philosophical Society, wrote, in his "Notes on Virginia," in refutation of the Abbé Reynal's assertion that America had "not produced one able mathematician, one man of genius in a single art or science": "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."

A committee of thirteen persons was appointed by the American Philosophical Society early in 1769 to view the transit of Venus, which was to occur on the 3d of June—a phenomenon which had been scientifically observed only twice before. This committee was divided into three, for observation at three stations—Philadelphia, Mr. Rittenhouse's home at Norriton, and the lighthouse near Cape Henlopen. Three other observers were associated with Mr. Rittenhouse at Norriton. An observatory was furnished, and the preparations and calculations preliminary to taking the observations were made by Mr. Rittenhouse. Some instruments were bought for the other stations. For Norriton a reflecting telescope was furnished by Mr. Maskelyne, Astronomer Royal at Greenwich—afterward given to the Philadelphia College—an astronomical quadrant by the Earl of Stirling, of East Jersey; and an equal-altitude instrument, a transit telescope, and a timepiece were made by Mr. Rittenhouse. The results of the observations were communicated to the American Philosophical Society, and a report of them was furnished to Mr. Maskelyne, who declared that they seemed excellent and complete, and did honor to the gentlemen who made them and to those who promoted the undertaking. The whole affair, in fact, gave the observers great credit abroad, and was regarded as promising well for the future of American science. The importance of the observation may be judged from the fact that it furnished one of the elements for verifying the great astronomical unit the earth's distance from the sun.

On the 9th of November following this observation a transit of Mercury—the fourth ever witnessed—was observed at Norriton by Mr. Rittenhouse and his fellow-astronomers, and a report on the subject was filed with the Philosophical Society. Shortly after this the difference of the meridians of Norriton and Philadelphia was determined by a committee, of which Mr. Rittenhouse was one, at the request of Mr. Maskelyne, who wished to connect the observations of the longitude of Norriton with those made by Messrs. Mason and Dixon in the course of measuring the degree of latitude.

About this time a scheme was started by Dr. Smith to induce Mr. Rittenhouse to remove to Philadelphia. Recommending him for appointment as a trustee of the Loan Office, then before the Assembly, Mr. Smith represented to the Speaker that he "ought to be encouraged to come to town, to take a lead in a manufacture, optical and mathematical, which never had been attempted in America, and drew thousands of pounds to England for instruments, often ill-finished; and it would redound to the honor of Philadelphia to take a lead in this, and of the Assembly to encourage it." The proposition was received enthusiastically, and the whole house rose to vote for Mr. Rittenhouse, one of the members exclaiming, "Our name is legion for this vote." The Assembly adjourned, however, without passing the bill, although Mr. Rittenhouse was afterward appointed to the position for which he was named in it. He removed to Philadelphia, on his own account, in the fall of 1770. The next scientific investigation in which he appears to have been engaged was the observation of the comet of 1770, of which he calculated the elements, and communicated the results to the American Philosophical Society. We afterward find him, with several other gentlemen, making experiments on the electric eel for the purpose of ascertaining the origin of the shock which the animal emits on being touched.

From this time on, Rittenhouse was to a considerable extent engaged in works in the service of the public, to some of which he was called in consequence of his scientific ability and mechanical skill, to others commended by his character as a citizen and his integrity. He was given charge of the State-House clock; appointed to survey the lands between the Susquehanna and Delaware Rivers; to superintend the improvement of the Schuylkill; and to determine the northwestern extremity of the boundary between New York and Pennsylvania.

In 1775 the American Philosophical Society presented to the Pennsylvania Assembly a plan for the erection of an observatory under State control, with Mr. Rittenhouse as "public astronomical observer"; describing him as "a gentleman whose abilities, speculative as well as practical, would do honor to any country. . . . Under his auspices the work could now be undertaken with the greatest advantages; and others may be bred up by him, to prosecute it in future times; but, if the present opportunity is neglected, perhaps whole centuries may not afford another. To rescue such a man from the drudgery of manual labor, and give him an occasion of indulging the bent of his genius with advantage to his country, is an honor which crowned heads might glory in; but it is an honor also, which it is hoped, in the case of a native, Pennsylvania would not yield to the greatest prince or people on earth." The Revolution came on, and the scheme was not carried out.

In view of that crisis, Mr. Rittenhouse was commissioned to prepare molds and have iron clock-weights cast, to be exchanged with the people for their leaden ones; as engineer to the Committee of Safety, to arrange for casting cannon; to view a site for the erection of a Continental powder-mill; to conduct experiments for rifling cannon and musket balls; to devise a method of fastening a chain for the protection of the river; to superintend the manufacture of saltpeter, and to locate a magazine for military stores. He was a member of the Committee of Safety in April, its vice-president in August, and its presiding officer in November, 1776. In 1776 he was a member of the Assembly from Philadelphia, and a member of the first Constitutional Convention of Pennsylvania; a member of the Board of War; and one of the Council of Safety, which had absolute powers. He was the first State Treasurer of Pennsylvania, from 1777 to 1789, when he declined to serve any longer. He was the first Director of the United States Mint, serving for three years from 1792; and he was called upon on several occasions to serve on commissions for the adjustment of boundaries. In connection with these public employments we find a curious letter from Mr. Jefferson to Mr. Rittenhouse, written in 1778, protesting against his wasting his abilities on affairs of state. "I am satisfied," he says, "that there is an order of geniuses above that obligation [to conduct government], and therefore exempt from it. No one can conceive that Nature ever intended to throw away a Newton upon the occupations of a crown. It would have been a prodigality for which even the conduct of Providence might have been arraigned, had he been by birth annexed to what was so far below him. . . . I doubt not there are in your country many persons equal to the task of conducting government; but you should consider that the world has but one Rittenhouse, and that it never had one before."

Mr. Rittenhouse was Professor of Astronomy in the University of Pennsylvania from 1779 till 1782, and was a trustee of the institution, continuing in that office after its reorganization in 1791. He was made one of the secretaries of the American Philosophical Society in 1771; became its vice-president in 1786; and succeeded Benjamin Franklin as president, on his death in 1790. He was elected a Fellow of the American Academy of Arts and Sciences in 1782, and an Honorary Fellow of the Royal Society in 1795. He received degrees from the College of Philadelphia, William and Mary College, and Princeton College.

He was tall and slender, quick in gait, had a countenance "indicative of intelligence, complacency, and goodness," and a disposition and manners that secured him friends and kept them. He bore testimony against the slave trade, and sympathized with the original motives of the French Revolution to such an extent that he assisted in the organization of the Democratic Society, and was made its president—but this was before the excesses of the Revolution were committed. While he might be called self-educated, lie was not, as Mr. Barton shows, wholly without assistance in pursuing his studies, although some writers had mistakenly affirmed this, but that assistance was small. Dr. Rush assumed, in the eulogy he pronounced upon him, that the eminence he attained was to be ascribed "chiefly to his having escaped the pernicious influence of monkish learning upon his mind in early life"; otherwise, "instead of revolving through life in a planetary orbit," he might have spent his time "in composing syllogisms, or in measuring the feet of Greak and Latin poetry." He understood the German and Low Dutch languages, acquired a reading knowledge of French, and "overcame in a great degree the difficulties of the Latin tongue." He was a firm believer in the Christian religion, though he was not attached to any church. That speculative disquisitions were of little interest to him is shown, perhaps, as much as by anything, by his remark concerning a conversation with a clerical gentleman, that it was "not, perhaps, greatly to the satisfaction of either of us; for he appears to be a mystical philosopher, and I, you know, care not a farthing for anything but sober certainty in philosophy." He published but little, because, as his biographer believes, he was too busy with work to give his time to the composition of formal papers. The list of his contributions to the American Philosophical Society includes twenty-two titles of papers relating to his orrery; the transits of Venus and Mercury; the comet of 1770; a method of deducing the true time of the sun's passing the meridian; the difference of longitude between the observations of Norriton and Philadelphia; an explanation of an optical deception; experiments on magnetism; a remarkable meteor seen in 1779; a comet observed in 1784; a new method of placing the meridian mark; an optical problem; astronomical observations (on the Georgium Sidus and a transit of Mercury); an account of several houses struck with lightning; another account of the effects of a stroke of lightning; several astronomical observations described in a single paper; a mathematical problem; a comet observed in 1793; the improvement of time-keepers; the expansion of wood by heat; a problem in logarithms; and the mode of determining the true place of a planet in an elliptical orbit—his last paper, read February 5, 1796. To these is added his oration on "Astronomy," delivered before the American Philosophical Society, on the 24th of February, 1775, and inscribed "To the delegates of the thirteen United Colonies." In this oration, three years before the announcement of Mayer's discovery of the proper motion of certain stars, and six years before Herschel's discovery of Uranus, the author put forth the suggestion, which has since proved a presage, that the fixed stars, and particularly the milky way, would afford fruitful fields of observation.