1822.] Historical Sketch of Electro-magnetism, 107 



Article IX. 



Historical Sketch of Electro-magnetism, 

 (To the Editor of the Annals of Philosophif.) 



MY DEAR SIR, 

 I XI EGRET that circumstances have occurred which have pre^- 

 vented me from completing the sketch of the history of electro- 

 m-dgnetism, of which you have already received a part. Much 

 has been done in this new branch of science since last April, up 

 to which time rny brief account goes, but I am not so circum- 

 stanced as to be able to give a fair account of it. As you wish 

 for the theoretical notices I had got together, I send them here- 

 with, leaving it with your discretion to use them as you think fit, 

 I. am yours very truly, M. 



(Concluded from vol. ii. p. 290, New Series.) 



Having, in the previous pages, endeavoured to give you such 

 an account of the experimental results as have been obtained by 

 the labourers in this new branch of science, 1 will now, in as 

 brief a manner as possible, state the theoretical views taken of 

 them by different philosophers as far as I can understand them. 

 The first attempt at a theoretical explanation of the phenomena, 

 which deserves attention, is that of M. Oersted. It cannot be 

 doubted for a moment by any one who has read the papers of 

 this philosopher both on the discovery and prior to it, that his 

 theory rather led to the experiments, than the experiments to the 

 theory. Chance indeed seems to have had very little to do with 

 the discovery except in retarding it, for the thoughts were con- 

 ceived, and the experiments devised, some time before they 

 were made. Notwithstanding all this, I have very little to say 

 on. M. Oersted's theory, for 1 must confess I do not quite under- 

 staLid it. Before the year 1807, a work was published by 

 M. Oersted, entitled, ''- An Inquiry into the Identity of Chemical 

 and Electrical Forces," and the eighth chapter of it is occu- 

 pied in considering the identity of the magnetic and electric 

 powers. In this work, M. Oersted proposed to try whether elec- 

 tricity the most latent, has any action on the magnet, and appears 

 to have considered the two powers as identical. 



When, however, the experiment had been successfully made, 

 M. Oersted was enabled to give a more defined form to his 

 theory, and his first paper* concludes with an hypothesis that will, 

 he thinks, readily explain all the phenomena. When a wire is 

 made to connect the two poles of a battery so as to discharge the 



• See Annals of Philosopht/, xvi. 276. 



