106 
ME. H. WILDE’S EXPEEIMENTAL EESEAECHES 
quantity and intensity armatures could easily be withdrawn from the magnet-cylinder, 
and interchanged, when required, in the course of a few minutes, the cross-head at the 
driving end of the machine being readily removeable for that purpose. 
74. Though the total weight of the 10-inch electro-magnetic machine complete is 
very considerable, being nearly 4*5 tons, yet its dimensions are comparatively small, since 
the entire length of the machine, including the brass cross-heads, is only 80 inches, its 
width 24 inches, and its height 60 inches. 
7 5. Experiments were first made with the machine, for the purpose of testing its power 
when the large electro-magnet was excited by magneto-electric and electro-magnetic ma- 
chines of various sizes.. The 10-inch machine, as well as the machines used for exciting 
it, were all driven from the same countershaft by means of pulleys of suitable dimensions. 
The intensity and quantity armatures (71, 72) were driven at a uniform velocity of 
about 1600 revolutions per minute, by means of a broad leather belt of the strongest 
description. The springs for taking the electricity from the 10-inch machine were con- 
nected, by means of large copper conductors, with two insulated plates of copper let into 
the under side of an experimental table. On the upper side of this table were two 
moveable brass studs, sliding in good contact with the copper plates, and forming the 
polar terminals of the machine. 
76. The quantity armature was first placed in the cylinder, and the springs were so 
arranged as to take the alternating currents of electricity from the polar terminals (16). 
The direct current from the small magneto-electric machine, having on its cylinder six 
permanent magnets, such as were used in the first series of experiments (12), was then 
transmitted through the coils of the electro-magnet of the 5-inch electro-magnetic ma- 
chine (63); and the direct current from the latter was simultaneously, and in like 
manner, transmitted through the coils of the electro-magnet of the 10-inch machine. 
77. This combination of the machines, when in full action, was attended by the deve- 
lopment of an amount of magnetic force in the large electro-magnet far exceeding any- 
thing which has hitherto been produced, together with the evolution of a quantity of 
dynamic electricity from the armature so enormous as to melt pieces of cylindrical iron 
rod 15 inches in length, and fully one-quarter of an inch in diameter. With the 
same arrangement, the electricity from the quantity armature also melted 15 inches of 
No. 11 copper wire 0T25 of an inch in diameter. 
78. When the intensity armature (71) was placed in the cylinder, the combination of 
the machines remaining the same as in the preceding experiments (76), the alternating 
current from the armature melted 7 feet of No. 16 iron wire 0‘065 of an inch in 
diameter, and made a length of 21 feet of the same wire red-hot. 
79. The illuminating power of the electricity from the intensity armature is, as might 
be expected, of the most splendid description. Two rods of gas-carbon, half an inch 
square, were placed in the carbon-holders of the beautiful apparatus for regulating the 
electric light, recently invented by M. Foucault, behind which was fixed a parabolic 
reflector 20 inches in diameter, so adjusted as to cause the rays of light to diverge from 
