The Newly-Discovered Force. 
190 
[April, 
disappeared, and could not, like this force, be drawn off 
from the sides of the conductor. 
Theories of the Force. 
Tne theory which Mr. Edison favours is that this spark 
indicates a radically new force, to which he has given the 
provisional name “ Etheric,” from its tendency to diffuse 
itself in various directions through matter. This theory 
would regard this force as distinct from any form of elec- 
tricity, as light or heat, and would indeed, bring it nearer to 
heat than to electricity, or would make it a kind of interme- 
diate between those two forces. In the ultimate analysis 
there is probably but one force, of which light, heat, and the 
different kinds of electricity are modifications — modes of 
motion, differing in the nature of their vibrations, correlated 
to and capable of being transformed into each other. The 
old-fashioned fluid theories of electricity, although they 
still hold ground in school and college text-books, have been 
long since abandoned by physicists, and in their place the 
theory that it is a mode of motion of the ether, and of other 
matter through which it circulates, is more in harmony with 
recent science. Already several varieties of electricity have 
been discovered as follows 
Frictional or statical electricity. 
Dynamical or current electricity (including galvanic, in- 
duced, and thermo electricity).* 
Induced electricity is farther subdivided into primary, 
extra, secondary, and tertiary currents, which differ from 
each other in quantity, tension, and in physiological effects. 
The tendency is for these different forms of electricity to 
approach to and actually run into each other. 
An eleCtro-magnetic apparatus is a reservoir of many 
forms of force — galvanic and induced electricity of various 
orders, magnetism, statical electricity, light, and heat. A 
source so rich in forces might give us at least one more ; it 
is possible that one more has been here discovered. When 
a strong galvanic current, connected so as to flow through a 
coil of wire, is closed, a magnetic field is evolved, in and near 
the coil and at some distance from it, the electricity being 
converted into magnetism ; when the circuit is open, the 
electricity, it has been supposed, is converted into heat ; it 
is probable that some of it is converted into this new force. 
* The statement recently made that thermo-electricity differs radically from 
any other form of electricity is incorredt. Thermo-electricity obeys the laws 
of dynamical electricity, however obtained. 
