THE COLLAPSE OF THE ELECTRIC LIGHT. 
157 
in the opposite direction as they recede. This alternate current 
is available for electric lights, but if it is desired to convert the 
current into one of continuity in the same direction a commu- 
tator is employed, operated by the vibrations of the fork, to change 
the circuit connections at each vibration, and thereby make 
the pulsations continuous on the line of one polarity. A portion 
of the current thus generated may pass through the helixes of 
the electro-magnets cl to intensify the same to the maximum 
power, and the remainder of the current is employed for any 
desired electrical operation wherever available. I, however, use 
the same, especially with my electric lights, but I remark that 
electricity for such lights may be developed by any suitable 
apparatus. I have represented commutator springs or levers, 
c 3, c 4, operated by rods that slide through the levers c 3, c 4, and 
by friction move them. When the prongs a 2, a 2 are moving 
from each other the contact of levers c 3, c 4 will be with the 
screws 40, 41, and the current will be from line 1 through cl to c, 
thence to c 3 to 41 , 43, and to circuit of electro-magnets d , d , and 
from d , d by 42 to 40, c 4, and line as indicated by the arrows. 
When the prongs a 2, a 2 are vibrating towards each other the 
circuit will be through c 1, c, c 3, 42, in the reverse direction 
through the circuit and magnets d , c£, back to 43, and by c 4 to 
line.” 
Now, the enormous loss of power in a system of magnets in 
alternating motion will be evident to every student of mechanical 
laws, as also its inferiority to the simple and regular function of 
rotation. Moreover, as is well remarked in the a Engineer,” the 
assumption that because a tuning-fork vibrates with small ex- 
penditure of power when free, it will do the same when moving 
in a dense magnetic field, is not only gratuitous but demon- 
strably false. Many other purely theoretical exceptions may be 
taken to the machine, such as the bulk of the tuning-fork used, 
and the impossibility of obtaining from it the necessary rapidity 
of vibration. It is in the lamp, however, that the principal 
interest centres, and this is now revealed, as had before been 
suspected, to depend on the incandescence of platinum or its 
alloys. The description given of it is as follows : — 
“ Platinum and other materials that can only be fused at a very 
high temperature have been employed in electric lights ; but 
there is risk of such light-giving substance melting under the 
electric energy. This portion of my invention relates to the 
regulation of the electric current, so as to prevent the same 
becoming so intense as to injure the incandescent material. 
The current regulation is primarily effected by the heat itself, 
and is automatic. In fig. 2 I have shown the light-producing 
body as a spiral, <x, connected to the posts b c, and within the 
glass cylinder g. This cylinder has a cap, l , and stands upon a 
