philosophical society of washington. 23 



5th Meeting. April 29, 1871. 



The President in the Chair. 



Admiral B. F. Sands communicated, in the name of Professor 

 Asaph Hall, au abstract of a paper 



ON THE ELEMENTS OF THE COMET I, 18Y1. 



(abstract.) 



This comet was discovered by Dr. Winnecke at Carlsruhe, 

 April 7th, and was also independently discovered by Mr. Lewis 

 Swift at Marathon, iS'ew York, on April 15th, 1871. Notice of 

 its discovery was received at the Naval Observatory April 19th, 

 and it was observed there on the 20th, 23d, and 24th, cloudy 

 weather preventing further observations. Although the observa- 

 tions are not well situated to give a good determination of the 

 orbit, the following elements have been computed : — 



Perihelion Passage, 1871, June 10, 496, Washington mean time. 



Longitude of Perilielion, 140O 49' 13" ) . ^ ^ . 



Longitude Ascending Node, 279 3 31 Apparent^ Equinox 



Inclination of Orbit Plane, 87 42 23 ) ^'^ 



Logarithm Perihelion Distance, 9.82206. 

 Motion Direct. 



Computing with these elements the Altona observation of April 

 9th, the following differences are found — 



dx = — 0'.8, and dB = -{- O'.l : 



from which it appears that these elements must be a tolerable 

 approximation to the truth. 



When first discovered the comet was about 95 degrees in true 

 anomaly from its perihelion, and is therefore approaching the 

 Sun, and the computations show that it is slowly approaching the 

 Earth. Its motion, how^ever, in heliocentric longitude is so small 

 that it will be apparently very near the Sun. Were it not for 

 this it might become visible to the naked eye after the next full 

 moon. Its distance from the Earth is about 1.8 of the Sun's 

 mean distance, and as it is easily observed in the telescope it is 

 in reality a bright comet. 



Mr. J. E. HiLGARD exhibited a chronoscope devised by Hippe, 

 of Neuchatel, and explained its application in the determination 

 of the rate of transmission of nerve-power. 



By request. Major King made a verbal report 



ON T^E CONSTRUCTION OF THE BRIDGE ACROSS EAST RIVER 

 BETWEEN BROOKLYN AND NEW YORK. 



