Page:Popular Science Monthly Volume 38.djvu/191

 added to the country's creative wealth. But, when this lazzarone is imported into the United States and set to grading an American railway, he is found to possess characteristics which may not have interfered with his usefulness on the Mont Cenis Tunnel, but which here become exceedingly unpractical, not to say uncomfortable: and which may, as we have shown, even prove as large a problem in our criminal, as his advent was, no doubt, a happy thought in our industrial, economy.



UR first thought, when we speak of the relations of light and electricity, is of the electric light. That is not the subject of the present paper. The physicist thinks of the extremely delicate reciprocal actions of the two forces, such as the rotation by the current of the plane of polarization, or the variation under the influence of light of the resistance of a conductor. In these cases, however, the action is not direct, but a medium, ponderable matter, is interposed. There are other closer, more intimate relations between the two forces. It is my purpose to discuss the proposition that light is in its very essence an electrical phenomenon—whether it be the light of the sun, of a candle, or of a glow-worm. Suppress electricity in the universe, light would disappear; suppress the luminiferous ether, electric and magnetic forces would cease to act through space. This theory is not of to-day or of yesterday, but has a long and instructive history. My own experiments only mark one of the steps in its development; and it is my purpose to retrace its whole evolution, not one of its phases only. It is not easy in a matter of this kind to be clear without omitting something essential. The phenomena to be considered take place in space, in the ether itself, and are not perceptible to the touch or the hearing or the sight. Reflection and reasoning may permit us to grasp them, but it is hard to make an exact description of them. We shall endeavor, therefore, to connect them with ideas that are already known to us. We refer, therefore, first to what we already know concerning light and electricity.

We know of a certainty that light is an undulatory movement, and that the undulations are transversal; we have determined their length and their velocity; and all that follows from