The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Turning Night Into Day

If we could examine this arc more closely we should see a whole stream of particles of incandescent carbon flowing from the negative to the positive rod. This makes a protuberance on the positive and a depression on the negative rod. The space between the rods becomes greater all the time, because the coal gradually burns up. To keep the arc from going out, the rods have to be brought nearer to each other every little while.

This arc is called the "Volta arc" in honor of a scientist named Volta.1
1.A Russian, Professor Petrov, discovered the volta arc at the same time as Davy. In the arc, just as in the flame of a kerosene lamp or a gas burner, it is incandescent carbon that gives the light. The difference is only that here the heat is supplied by an electric current Instead of by fire.

Complicated Lamps Return

At first this arc was only an interesting scientific experiment. It was not possible to use it in lighting because the coal burned up too fast. It was about thirty years before a certain scientist, this time a Frenchman instead of an Englishman, used coke in the place of coal. Coke is what is left after the coal has been burned in gas-plants for making illuminating gas.

Now coke burns more slowly. But this was not all that was necessary. Some way must be devised for keeping the rods near enough to each other all the time. So we find clockworks again used in a lamp. This time to keep the ends of the rods equally distant from each other.

They tried lighting the streets of Paris with arc lamps provided with a clock mechanism. One square was lighted up but the mechanism was so costly that it had to be abandoned.

A German Scientist, Gephner Altenek, devised a much cleverer way of keeping these rods near enough together. His arc lamp was so complicated that it would take too long and be too difficult to explain it. The essential thing in it was that he put a magnet in his lamp which (at the necessary time) attracted an iron strip attached to one of the rods. The distance between the rods was thus diminished and the lamp continued to work.