DOVE OX THE ELECTRICITY OF IXDUCTION. 103 



other's action. The disturbance of equiUbrium on the introduc- 

 tion of iron into one of the previously empty coils, must there- 

 fore be the etfect of this iron alone. The results uliich I ob- 

 tained when the primary current was that of a galvanic circuit, 

 or of a thermo-electric circuit, I presented to the Academy on the 

 24th of October 1839. They were of such a nature as to make 

 it appear desirable that the experiments should be extended to 

 other modes of magnetizing the iron than by the current of a 

 galvanic circuit. The results obtained by the discharge of an 

 electric battery were laid before the Academy on the 28th of 

 October 1841, those obtained by approaching the iron to a mag- 

 net on the 18th of April 1842. By means of this last method of 

 magnetizing, similar experiments could be instituted upon the 

 primary extra current. The increased physiological action of 

 secondary currents of higher orders by means of bundles of iron 

 wires, was lastly the subject of a memoir laid before the Aca- 

 demy on the 1 1th of August, 1842. All these researches, form- 

 ing together a complete whole, are here collected, with the 

 consent of the Academy, into one memoir, in which that order 

 has been followed which appeared to show the subject in the 

 clearest light ; the order in which they were first published will 

 appear by the reports of the Academy*. 



It is well known that electric currents of different origin 



• Upon a magneto-electric apparatus for producing induced currents of equal 

 intensity in wires completely separated from eacli other, and upon the applica- 

 tion of mutually compensating coils in general. ISOS, pp. 21 and 95. 



Upon the relation of gray and white cast iron to malleable iron, to hard and 

 soft steel with reference to the phaenomena of induction which they produce. 

 1839, p. 72. 



Upon magneto-electrical currents, which, when in equilibrium as regards the 

 galvanometer, produce powerful shocks upon the human body, and, on the con- 

 trary, when their physiological action is mutually compensated, powerfully 

 affect the magnetic needle. 1839, p. 163. 



Upon the induced currents excited on magnetizing iron by means of fric- 

 tional electricity. 1841, p. 296. 



Upon the extra current at the commencement and close of a primary current. 

 1842. p. 99. 



Upon the induced electric currents caused by the approach of massive iron 

 or of a bundle of iron wire to a steel magnet. 1842, p. 112. 



Upon the electric currents which the evanescent magnetism of electro- 

 magnetized rods of iron or bundles of wires induces when the current which 

 magnetizes them is produced, — 



1. iJy the approach of a closed copper wire to a steel magnet; 



2. By the ap|)roach of soft iron to a steel magnet; 



3. By the combination of both agencies by means of Saxton's machine. 

 August 1842. 



Upon the action of iron rods and bundles of wires upon induced currents of 

 Iiiglier orders. August 1812. 



