Page:Popular Science Monthly Volume 36.djvu/859

Rh 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