504; PROF. JACOBI ON THE APPLICATION OF ELECTRO-MAGNETISM 



only from 30 to 40 at most : nevertheless, these feeble magnets furnished 

 me with a mechanical action equal to Imlf the force of a man. To main- 

 tain this action, during eight hours, scarcely half a pound of zinc is 

 required, everything being properly arranged, 



I have not yet been able to construct a larger apparatus, and I there- 

 fore wished to make as much use as I could of the one I possessed, since 

 it was capable of showing completely the nature of the active forces. 

 My experiments may be easily repeated ; all depending upon carefully 

 attending to the construction of the commutator, and likewise that of 

 the galvanic apparatus. Those who are acquainted with electro-mag- 

 netic phaenomena will easily be able to make the necessary arrangements, 

 and to give the accurate proportion to the several parts. The object of 

 this memoir will be attained if it inspire an interest for a subject which 

 merits it. 



Kbnigsberg, August 21, 1835. 



MEMOIR. 



1. 



In November ISS'i I had the honour to lay before the Academy of 

 Sciences of Paris a note upon a new electro-magnetic apparatus. That 

 note was read at the meeting of December 1st; and an abstract of 

 it was printed in the Institute, No. 82, of December 3rd, to which I 

 refer. Since that time MM. Botto and dal Negro have claimed the 

 priority of the invention, the former in the Institute (No. 110) of June 

 I7th. The competition in which I find myself engaged with such di- 

 stinguished men serves only to confirm my conviction of the importance 

 of this new motive power. A discussion as to priority is only of histo- 

 rical interest. It is not astonishing that persons, who had scarcely any 

 communication with each other, should have devoted themselves almost 

 at the same time to the study of the same object. But we ought not to 

 conceal from ourselves that, after the grand discovery of M. Oersted 

 and the experiments of Mr. Sturgeon, who, it seems to me, first gave a 

 great magnetic intensity to soft iron by means of an electric current, and 

 viewing the instantaneous manner in which this magnetism may be de- 

 stroyed or reversed, by merely changing the direction of the current, — it 

 was not difficult to conceive the possibility that some motion or some me- 

 chanical operation might be produced by the electro-magnetic excita- 

 tion of soft iron. In short we must award the palm to M. Oersted ; 

 whilst we who follow him shall have the merit of having known how to 

 apply this new power to practical purposes and the wants of life : 

 and this will be reserved for him who shall best have understood the 

 mechanical and pliysical principles of this motive pow6r. 



