Page:Popular Science Monthly Volume 66.djvu/66

62 definite and intelligible mechanical basis which physicists have been able to form of an electric charge is that which regards it as a phenomenon of the ether, this form of speculation is but a return under another name to views which had earlier proved attractive to some of the most brilliant minds in the world of science, such as Helmholtz and Kelvin. The idea of the atom, as a vortex motion of a perfect fluid (the ether), and similar speculative conceptions, whatever be the precise form of mechanism imagined, are of the same class as the moving electric charge of the later theorists.

Lodge in a recent article in which he attempts to voice in a popular way the views of this school of thought says:

"Electricity under strain constitutes 'charge'; electricity in locomotion constitutes light. What electricity itself is we do not know, but it may, perhaps, be a form or aspect of matter. . . . Now we can go one step further and say, matter is composed of electricity and of nothing else. . . ."

If for the word electricity in this quotation from Lodge we substitute ether, we have a statement which conforms quite as well to the accepted theories of light and electricity as his original statement does to the newer ideas it is intended to express.

This reconstructed statement would read as follows:

Ether under strain constitutes 'charge'; ether in locomotion constitutes current and magnetism; ether in vibration constitutes light. What ether itself is we do not know, but it may, perhaps, be a form or aspect of matter. Now we can go one step further and say: Matter is composed of ether and of nothing else.

The use of the word electricity, as employed by Lodge and others, is now much in vogue, but it appears to me unfortunate. It would be distinctly conducive to clearness of thought and an avoidance of confusion to restrict the term to the only meaning which is free from criticism; that in which it is used to designate the science which deals with electrical phenomena.

The only way in which the noun electricity enters, in any definite and legitimate manner into our electrical treatises is in the designation of Q in the equations

Here we are in the habit—whether by inheritance from the age of the electric fluid, by reason of the hydrodynamic analogy or as a matter of convention or of convenience merely—of calling Q the quantity of electricity.

Now Q is 'charge' and its unit the coulomb is unit charge. The alternative expression, quantity of electricity, is a purely conventional designation and without independent physical significance. It owes its