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 half the force of aman. To main- 
tain this action, during eight hours, scarcely half a pound of zine 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 phenomena 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. 
Konigsberg, August 21, 1835. 
MEMOIR. 
1. 
In November 1834 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 Ist; 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 
17th. 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 physical principles of this motive power. 
