in Magnetism and Electricity. 95 



net performs statically in the case of the magneto-electric 

 machine. 



51. That the charge retained by the electromagnet is, as has 

 already been observed, much more powerful than that which the 

 magneto-electric machine is of itself capable of producing, is evi- 

 dent from the severe shock which is felt when the body forms 

 part of the circuit, and also from the more voluminous spark 

 which appears at the point of disjunction of the wires when con- 

 tact with the machine is broken. 



52. That this increase of electric force in the electromagnet is 

 the consequence or effect of a certain number of electrical waves 

 transmitted through the electrohelices, and succeeding each 

 other with sufficient I'apidity to sustain the increasing flux of 

 magnetism in the iron, is manifest from the time which elapses 

 before the electricity transmitted through the helices attains a 

 permanent degree of intensity, and before the electromagnet ac- 

 quires its greatest amount of magnetism (45)*. 



53. That the length of time which was observed to elapse, and 

 the number of waves which required to be transmitted through 

 the electrohelices before the current from the magneto- electric 

 machine attained a permanent degree of intensity, and the elec- 

 tromagnet acquired its greatest amount of magnetism, are de- 

 pendent upon the magnitude of the waves of electricity trans- 

 mitted through the electrohelices, is evident from the fact that 

 the same degree of intensity of the current (as measured by 

 the balance), and the same amount of magnetism in the electro- 

 magnet, were obtained with a much smaller number of waves, 

 and in a shorter time, from a large electromotor, than could 

 be obtained with a much greater number of waves from a small 

 electromotor (46). These observations will be further confirmed 

 by experiments to be hereafter adduced. 



54. The cause of the great difference between the attractive 

 force of a permanent magnet and that of an electromagnet ex- 

 cited through its agency, and also the agreement of the pheno- 

 mena with the principle of the conservation of force, now become 

 sufficiently manifest to render it unnecessary, at the present 

 time, to institute a more rigorous comparison between the quan- 

 tities of magnetism and electricity of the magneto-electric ma- 

 chine, and the quantities of the same forces developed in the 

 electromagnets (23, 33). The general conclusion which may, 

 however, be drawn from a consideration of the preceding expe- 

 riments is, that when an electromagnet is excited through the 

 agency of a permanent magnet, the large amount of magnetism 

 manifested in the electromagnet simultaneously with the small 

 amount manifested in the permanent magnet is the constant ac- 



* Philosophical Transactions, 1846, p. 6. 



