3S2 



Astronomical Society of London. 



equator, it becomes magnetic. If we rightly heard the paper, 

 it is necessary to the success of these experiments that the 

 Galvanic current be sent not along the bar, but at right angles 

 to it, across its middle: that is, wiiile the direction of the bar is 

 east and west, that of the Galvaijic current must be north and 

 south. 



These experiments were made in the laboratory of the Royal 

 Institution, and also at the London Institution. They will be 

 understood from the following description : 



When an electrical or a Voltaic battery of considerable quantity 

 is charged, the compensating or discharging wire becomes mag- 

 netic upon the completion of the discharge. 



Common needles or small bars of steel placed transversely on 

 the wire, or under it, or on its sides, become permanent magnets 

 on the discharge. 



If the quantity of electric fluid be very great, contact with the 

 wire is not requisite. In one instance magnetism was commu- 

 nicated at fourteen inches distance from the conducting wire. It 

 was also communicated through plates of glass, and even when 

 the bars or needles were immersed in water. 



The annexed simple diagram may perhaps be useful to show 

 the peculiarity of polarization, as it follows steadily the rule in- 

 dicated. 



P Positive end, 71 negative end. 

 NS Bar on the wire — N north, S south. 

 SN Bar under the wire — S south, N north. 

 S N 



Compensating wire. 



N S 



At the London Institution the electrical batteries used were 

 from 18 cubic feet to 70 cubic feet. The Voltaic were 12 troughs 

 of four-inch plates, mounted with double coppers agreeable to 

 Dr. Wollaston's plan. 



ASTRONOMICAL SOCIETY OF LONDON. 



Nov. 10. — The members of this Society met, for the first time 

 this season, at their new apartments in Lincoln's Inn Fields. A 

 notice was read respecting the Pleiades ; in which it was stated 



that 



