The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Turning Night Into Day
As you see, work on the arc lamps was going on in all the countries of Europe. Here in Russia an inventor by the name of Yablochkov was working on them. He figured out that the rods should not be arranged one above the other, but side by side, parallel, as shown in the picture. To keep the distance between them from changing he would pass the current first into one and then into the other side. Thus the rods would be alternately positive and negative and first one then the other would burn up more rapidly. The rods were separated from each other by a strip of gypsum which was gradually volatilized by the intense heat of the candle.
These "candles" of Yablochkov gave a beautiful rosy or violet light. They were greeted with the greatest enthusiasm at an exposition in Paris.
The Tables Are Turned
There was a time when people racked their brains over the problem of getting lamps to give a brighter light. And now, several hundred years later, we find scientists doing precisely the opposite. The trouble was that these arc lamps were too bright. You can't put a six hundred candlepower lamp on your writing desk. It might put your eyes out and how expensive it would be!
Some way must be found to make the light of the electric lamp less brilliant. So they figured out that it would be simpler to bring the carbon itself to an incandescent heat by means of the electric current, doing away with the arc entirely.
If an electric current is sent through a slender carbon filament, the carbon becomes heated. When the temperature reaches 550° C. it begins to give off light. This light is at first red, then it grows whiter and whiter, until finally when a very high temperature is reached it is entirely white. In a word, the same thing occurs as when we heated our poker in the stove.
So they began trying to send the current through the carbon filament. But the filament burned up at once and the lamp went out. To prevent this it was necessary either to exhaust the air or to fill the lamp with some gas which would not support combustion, for example, nitrogen.
Kerosene and oil lamps need air, just as a person does. Without air there cannot be a flame. But here it is just the opposite—air does harm because no flame or combustion is desired. For, you see, the filament is heated by the electric current, not by a flame.
The first good lamp using a carbon filament was invented fifty years ago by the famous American inventor, Thomas Alva Edison. He used a carbonized bamboo filament. To keep this filament from being burned up, Edison very carefully exhausted all the air from the lamp.
