PROCEEDINGS 
OF 
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. 
Ir was Resotvep,—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. 
__L. 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: 
Pa _ m’ ae 
1 gpl ees mY RI (1) 
: He had, at that time, deduced from this equation the known 
VOL. II. 2y¥ 
