IN MAGNETISM AND ELECTRICITY. 
99 
45. But if the retardation of the current, as indicated by the balance when placed in 
the middle of the circuit, had been the effect of an accumulation of static electricity in 
the electro-helices, it would also have been instantly attended by a rush of the full 
current of electricity into the helices at the beginning of the circuit, such as was observed 
in the before-mentioned experiments made by Faraday (40). On making the experi- 
ment this was not, however, found to be the case ; for when the balance was removed from 
the middle and placed at the beginning of the electro-magnetic circuit, the wires being 
again joined up so as to form a continuous helix as before (33), it was still found that 
1*5 second, and with the large electro-magnet (67, 68) 15 seconds, elapsed before the 
electricity acquired sufficient power to bring down the submagnet of the balance. 
46. When the large electro-magnet (67, 68) was excited by the electricity from a 
larger and more powerful machine (63), driven at a velocity of 2000 revolutions (equi- 
valent to 4000 waves) per minute, instead of that from the small magneto-electric 
machine, which produced 6000 waves per minute, an interval of only four seconds 
elapsed before the balance responded to the attractive force of its electro-magnet. 
47. Moreover, the direction of the current in the electro-helices, as shown by the gal- 
vanometer, was the same after as it was before connexion with the electromotor was 
broken; whereas had the current, as shown by the spark obtained (38), been the result 
of a static charge of the kind observed in insulated telegraph wires, the electricity would 
have discharged itself, when the place of disjunction was at the electromotor, in the 
opposite direction to that in which it entered the electro-helices. 
48. The conclusions drawn from a consideration of these experiments are therefore 
opposed to the supposition that the effects described are the consequence of a static 
charge of the kind observed to be retained by insulated submarine and subterranean 
telegraph wires ; but some of the phenomena described, — such as the retardation of the 
current when contact was made with the magneto-electric machine (43, 45), and the 
exalted electrical condition of the wire surrounding the electro-magnet, as shown by the 
voluminous spark seen and the severe shock felt when contact with the machine was 
broken (37), — are identical with the phenomena of electric induction observed by Dr. 
Henry* and investigated by Faraday with the aid of the voltaic battery, and which 
form the subject of his Ninth Series of Researches in Electricity f. 
49. That an electro-magnet possesses the power of retaining a charge of electricity in 
a manner analogous to that in which it is retained in insulated submarine cables and in 
the Leyden jar, but not identical with it, is evident from the appearance of a spark at 
the point of disjunction of the wires a considerable time after all connexion with the 
electromotor has been cut off. The production of this spark appears to me to arise 
from the comparatively slow manner in which large masses of iron return to their normal 
condition after having attained a highly exalted degree of magnetism ; the rate of 
decrease, however, being sufficiently rapid to allow the induction-current to manifest 
Silliman’s American Journal of Science, 1832, vol. xxii. p. 408. 
f 'Philosophical Transactions, 1835, vol. cxxv. 
o 2 
