DAVID RITTENHOUSE. 53 



did honour 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. Maske- 

 lyne, 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. Recom- 

 mending 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 honour 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, how- 

 ever, 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 com- 

 municated 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 ascertain- 

 ing the origin of the shock which the animal emits on being 

 touched. 



