Mr Christie on the Effect of Rot ution on Magnetic Forces. 135 



main subject of his researches, is not referable to any ordinary 

 cause with which we are familiar at the present day ; it is, 

 therefore, one of the most interesting objects of the naturalist, 

 either to confirm the views which would refer the origin of it 

 to the Mosaic Deluge, or to show that it may have arisen from 

 some convulsion of a less general nature, yet sufficient to ac- 

 count for the immense distance to which large boulders have 

 been removed from their native beds. And although the 

 Cervus Euryceros has undoubted claims to a postdiluvian 

 origin, we are by no means entitled to suppose, that there may 

 not exist the relics of other animals, which, being found under 

 perfectly different circumstances, may justify an opposite con- 

 clusion. In short, the whole subject admits of further investi- 

 gation. I am, &c. 



Samuel Hjbbert. 

 Edinburgh, May 20, 1825. 



Art. XXVII. — Notice of Mr Christie $ Discoveries respecting 

 the Effect of Rotation on the Magnetic Forces. 



In a valuable paper in the last part of the Philosophical 

 Transactions " On the Effects of Temperature on the Inten- 

 sity of Magnetic Forces, and on the Diurnal Variation of the 

 Terrestrial Magnetic Intensity? of which we have given the 

 leading results in our Scientific Intelligence, Mr Christie has 

 mentioned the curious fact, that iron acquires peculiar mag- 

 netic properties by simple rotation, which we understand he 

 discovered and communicated to a friend more than three 

 years before this paper was written. Mr Christie has since 

 drawn up an account of the numerous experiments which he 

 made in order to discover the" laws according to which the ro- 

 tation of iron affected a magnetic needle under its influence, 

 which has been lately read before the Royal Society. The 

 first observations which he made established the fact, that if 

 a plate of iron be made to revolve about an axis passing 

 through its centre, then, when it is brought to rest, a magne- 

 tic needle in its vicinity will be found to deviate differently, 

 according as the plate has been made to revolve in one direc- 



