OF ARTS AND SCIENCES. 353 



Five Iiundred and first meeting. 



December 9, 1861. — Monthly Meeting. 



The Vice-President in the chair. 



The Corresponding Secretary read letters of acceptance from 

 Chief Justice Bigelow, Commander J. M. GiUiss, U. S. N., 

 Professor James Hadlcy, Jr., Ezra Abbot, Truman H. Saflford, 

 and Jules Marcou, who had been notified of their election into 

 the Academy. 



Professor Cooke was added to the Committee on Captain 

 Anderson's paper, on motion of Professor Peirce. 



Messrs. Peirce, Bond, Levering, Winlock, J. I. Bowditch, 

 and B. A. Gould were appointed a committee to wait upon 

 Mr. Alvan Clark, and, with his consent, to examine and report 

 upon a new and large telescope said to have been constructed 

 by him. 



Professor Peirce presented the following 



Abstract of a Memoir upon the Attraction of Saturn'' s Ring-. 



The general formula for the attraction of the ring is expressed by 

 the aid of elliptic integrals. 



When the attracted point is in the plane of the ring, the formula of 

 attraction assumes the simple form, 



Ji = Ro — Ri , 

 in which 



i?„. = K \l±-B^ E'c^ — ^' + P''" F^c^ . 

 V 1- r (r + p„,) '"J 



In this formula 



r = the distance of the attracted point from centre of ring, 

 po = the exterior radius of the ring, 

 Pj = the interior radius of the ring, 



br. log. ir^ 7.317409. 

 VOL. V. 45 



