Curiosities of Science. 199 



the rays of the full moon on the magnetic needle, when he found 

 it was nve degrees attracted by it. 



MAGNETO-ELECTRICITY. 



In 1820, the Copley Medal was adjudicated to M. Oersted 

 of Copenhagen, "when," says Dr. Whewell, "the philosopher 

 announced that the conducting-wire of a voltaic circuit acts 

 upon a magnetic needle ; and thus recalled into activity that 

 endeavour to connect magnetism with electricity which, though 

 apparently on many accounts so hopeful, had hitherto been at- 

 tended with no success. Oersted found that the needle has a 

 tendency to place itself at right anyles to the wire ; a kind of 

 action altogether different from any which had been suspected." 



ELECTRO-MAGNETS OF THE HORSE-SHOE FORM 



were discovered by Sturgeon in 1825. Of two Magnets made by 

 a process devised by M. Elias, and manufactured by M. Loge- 

 meur at Haerlem, one, a single horse-shoe magnet weighing 

 about 1 lb., lifts 28 \ Ibs. ; the other, a triple horse-shoe magnet 

 of about 10 Ibs. weight, is capable of lifdng about 150 Ibs. Si- 

 milar magnets are made by the same person capable of sup- 

 porting 5 cwt. In the process of making them, a helix of 

 copper and a galvanic battery are used. The smaller magnet 

 has twice the power expressed by Haecker's formula for the 

 best artificial steel magnet. 



Subsequently Henry and Ten Eyk, in America, constructed 

 some electro-magnets on a large scale. One horse-shoe magnet 

 made by them, weighing 60 Ibs., would support more than 

 2000 Ibs. 



In September 1858, there were constructed for the Atlan- 

 tic-telegraph cable at Valentia two permanent magnets, from 

 which the electric induction is obtained : each is composed of 

 30 horse-shoe magnets, 2 feet long and from 4 to 5 inches 

 broad ; the induction coils attached to these each contain six 

 miles of wire, and a shock from them, if passed through the 

 human body, would be sufficient to destroy life. 



ROTATION-MAGNETISM. 



The unexpected discovery of Rotation- Magnetism by Arago, 

 in 1825, has shown practically that every kind of matter is sus- 

 ceptible of magnetism ; and the recent investigations of Fara- 

 day on diamagnetic substances have, under special conditions 

 of meridian or equatorial direction, and of solid, fluid, or gaseous 

 inactive conditions of the bodies, confirmed this important re- 

 sult. 



