Popular summary of' Experiments, Sfd 13 



Art. II.— A Popular Summary of the Experiments of Messrs 

 Barlow, Christie, Babbage, and Hcrschel, on the Magne- 

 tism of Iron and other Metals, as exhibited by Rotation. 



There are few branches of modern science that are likely to 

 excite a greater interest than that which relates to the influence 

 of rotation on the phenomena of magnetism. We are proud 

 to think that this remarkable discovery was first made in our 

 own country, and that, with the exception of a few important 

 experiments made in France, it has been prosecuted solely by 

 the Fellows of the Royal Society of London. At no period 

 of its history, perhaps, has this distinguished body exhibited 

 such a display of pre-eminent and varied talent. In the high- 

 er mathematics, in the nicest manipulations of chemistry, and 

 in the most recondite branches of physics, it can now boast 

 of names which posterity will pronounce with reverence, and 

 cherish with affection. 



The Transactions of the Royal Society, for the year which 

 is now about to close, cannot fail to excite such feelings in 

 the minds of those who peruse them, and particularly that part 

 which contains the valuable memoirs, of which we now pro- 

 pose to give a brief and popular summary. 



It fortunately requires no mathematical knowledge, and no 

 stretch of intellect, to comprehend the principal results of these 

 investigations, and as the experiments address themselves in a 

 peculiar manner to the eye, they are likely to be repeated 

 and extended wherever a magnet and a turning lathe can be 

 procured. 



In the year 1818, when Mr Barlow first proposed the cir- 

 cular plate of iron for correcting the local attraction of ves- 

 sels, he found that, as the plate was made to turn upon its 

 centre, different parts of its circumference had different de- 

 grees of magnetic action on the compass, and, for this reason, 

 he has, from the first, employed a double plate, so as to be 

 enabled to combine the strong part of one plate with the 

 weak part of the other, in order thereby to equalize the pow- 

 er in every part. * In repeating and extending these experi- 



* Sec Essay on Magnetic Attraction, 1st ed. p. 90. 



