SKETCH OF DAVID RITTENHOUSE. 839 



supposed Mr. Rittenhouse second to no astronomer living ; that in 

 genius lie 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 Ameri- 

 can 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 sta- 

 tions Philadelphia, Mr. Rittenhouse's home at Norriton, and the 

 lighthouse near Cape Henlopen. Three other observers were as- 

 sociated 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 Jer- 

 sey ; and an equal-altitude instrument, a transit telescope, and a 

 timepiece were made by Mr. Rittenhouse. The results of the ob- 

 servations 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 pro- 

 moted the undertaking. The whole affair, in fact, gave the ob- 

 servers great credit abroad, and was regarded as promising well 

 for the future of American science. The importance of the obser- 

 vation 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 Phila- 

 delphia 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 



