PROCEEDINGS 



THE ROYAL IRISH ACADEMY. 



November 11th, 1850. 



HUMPHREY LLOYD, D.D., President, 

 in the Chair. 

 On the recommendation of the Council, 



It was Resolved, — 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, the variations 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 



* Proceedings of the Royal Irish Academy, vol. ii. p. 210. 

 VOL. V. B 



