169 



Sir William R. Hamilton handed in the following diagram, 

 representing (rudely) the manner in which the planet Metis 

 was seen on April 28, 1848, in an inverting telescope : 



/ 



*c 



b* 





e 



* 

 /* 



d 



• 



p* (Metis.) 





*a 





*9 





On April 30, 1848, the other seven stars, a, b, c, d, e,/,g, 

 of this group, retained their respective positions ; but the 

 planet Metis had withdrawn from the position p, and had left the 

 (circular) ^eW indicated above, in the direction of the arrow. 



The planet was thus seen at the Observatory of Trinity 

 College, Dublin, in consequence of information from the dis- 

 coverer, Mr. Graham, principal assistant to E.J. Cooper, Esq. 



Mr. Donovan read a paper " On several Improvements 

 in the Construction of the Galvanometer ; on Galvanometers 

 generally ; and on a new Instrument for measuring arid ascer- 

 taining the Distribution of Magnetism in Needles intended 

 to be astatic, and for communicating to them greater sensi- 

 bility." 



The galvanometer, in the present day, has become a most 

 important instrument of research, whether it be considered as 

 a measure of electricity or of heat. In the latter capacity it 

 exceeds all others in sensibility, and the promptness of its in- 

 dications. But the construction at present in use is liable to 

 the interference of circumstances which lessen its sensibility, 



