PROCEEDINGS 



THE ROYAL IRISH ACADEMY. 



1846-7. No. 68. 



June 14th, 1847. 



REV. HUMPHREY LLOYD, D. D., President, in the 

 Chair. 



Arthur Sidney Ormsby, Esq., and John C. Egan, Esq., 

 were elected Members of the Academy. 



It was Resolved, — That the Secretary of the Academy 

 be requested to prepare a draft of an Address to His Excel- 

 lency the Lord Lieutenant, to be submitted to the Academy 

 at its next Meeting. 



Sir William Rowan Hamilton made a communication re- 

 specting the application of the Calculus of Quaternions to the 

 Theory of the Moon. 



I. At two Meetings of the Royal Irish Academy, in the 

 month of July, 1845, Sir William Rowan Hamilton had exhi- 

 bited and illustrated the following general equation of motion 

 of a system of bodies, with masses m, m', . . , and with vec- 

 tors a, a', . . , and attracting each other according to New- 

 ton's law : 



^-2 ^ m 



He had, at that time, deduced from this equation the known 

 VOL. in. 2 Y 



