PROCEEDINGS 
OF 
THE ROYAL IRISH ACADEMY. 
MONDAY, NOVEMBER 9, 1857. 
James Hentuorn Topp, D. D., President, in the Chair. 
- Own the recommendation of the Council the following Resolutions were 
adopted :-— 
1. To authorize the Treasurer to pay a sum of £41 5s. 11d., to 
liquidate the Balance of the cost of printing the Museum Catalogue 
and arranging the Museum,—this sum being in addition to the sum of 
£250 voted on the 16th March last. 
2. That all moneys derived from the sale of the Catalogue, after 
the expenses of Adyertising, &c., be devoted to the publication of the 
second part of that work. 
Rev. R. Carmichael read a paper on some Brief Methods in the In- 
tegral Calculus. 
Sir W. R. Hamilton gave an account of some researches of his own 
on the Theory of Definite Integrals. 
MONDAY, NOVEMBER 30, 1857. (SraTep MEETING.) 
James Henroorn Topp, D.D., President, in the Chair. 
Tn consequence of the unavoidable absence of the author, the follow- 
ing paper by the Rey. T. R. Robinson, D. D., was read by the President— 
ON THE LIFTING POWERS OF ELECTRO-MAGNETS. 
This paper constituted the third part of Dr. Robinson’s researches 
on the lifting power of the Electro-magnet, In it he examines the de- 
pendence of this power on the length and inductivity of the magnetic 
circuit which is formed when the poles are connected by a keeper. 
Whatever lessens the inductivity, lessens the magnetic power. If the 
circuit be incomplete, or if the middle of the keeper or of the magnet be 
brass, the power decreases to 0°70 or 0°08, or even to 0:02 of its normal 
amount. Plates of brass 0'12 thick interposed between the keeper and 
poles produce a similar effect; and even the minute interval which re- 
R. I, ACAD. PROC.—YVOL. VII. B 
