oe. 
+e 
PROCEEDINGS 
OF 
THE ROYAL IRISH ACADEMY. 
NovemBer 1I1Tu, 1850. 
HUMPHREY LLOYD, D.D., Presivent, 
in the Chair. 
On the recommendation of the Council, 
Ir was Resotvep,—That a sum not exceeding £75 be 
granted for the purpose of defraying the expenses incurred in 
the erection of the meteorological and tidal instruments. 
The President read the following paper on the induction 
of soft iron, as applied to the determination of the changes of 
the earth’s magnetic force. 
«To determine completely the laws of the changes to which 
_ the earth’s magnetic force is subject, observation must furnish 
“the values of three distinct elements. Of these, thev ariations in 
the direction and magnitude of the horizontal component are 
- completely determined by the methods given by Gauss and 
others; but, until lately, no satisfactory means had been de- 
vised for the determination of the variations of the remaining 
element. The principle of the method by which, as I con- 
ceive, this desideratum is now supplied, has been already sub- 
mitted by me to the notice of the Academy ;* but as the 
mode of applying it has since undergone many important 
5 aan en enn 
* Proceedings of the Royal Irish Academy, vol. ii. p. 210. 
VOL. V. ; B 
