SIMPLE EXPLANATION OF ELECTRIC LAMPS.

Patea Mail, 7 July 1882, Page 4

SIMPLE EXPLANATION OF ELECTRIC LAMPS.

If we examine one of the electric lamps in the streets, we shall find it consists of two rods, one pointing upward from the bottom of the lamp, the other hanging downward. The rods seem to touc*., and the brilliant flame is exactly where they seem-to meet. Once a day a man comes around with a bag on the rods. He takes out the old rods that were burned the night before, and places a new set in each lamp. After he has gone about, as if he were patting new Wicks into the lamps, and each is ready for its night’s work, all the lamps are lighted in broad day, to see that every one is in proper trim. They are allowed to burn until the men have walked about in the streets and looked at each lamp. If all are burning well, they are put out until it begins to grow dark. If it fails to burn properly, a man goes to that lamp to see what is the matter. The rods are made of a curious black substance, like charcoal, that is called carbon. . When the lamp is out the rods touch each other. In order to light the lamp, they are pulled apart ; and if you look at the flame through a smoked glass, you will see that the rods do not quite touch. There is a small space between their points, and this space is filled with fire. Look at the other parts of the rods, or the copper wires that extend along the streets. They have no light, no heat, no sound. The wires are cold, dark, and silent. If we were to push the two rods in the lamp close together, the light and heat would disappear, and the curious hissing sound would stop. Why is this ? Let us go to the wood near some brook, and it may be that we can understand this matter.

Here is the brook, flowing quietly along, smooth, deep, and without a ripple. We walk beside (he stream and come to a place where there are high rocks and steep stony banks. Here the channel is very narrow and the water is no longer smooth and silent. It boils and foams between the rocks. There arc eddies and whirlpools, and at last we come to the narrowest part of all. Here the once dark and silent water roars and foams in white stormy rapids. There are sounds and furious leaping and rushing water and clouds of spray. What is the matter ? Why is the smooth dark water so white with rage, so impetuous, so full of sounds and turmoil ? The rocks are the cause. The way is narrow and steep. The waters are hemmed in, and there is a grand display of flashing white foam and roaring waterfalls, as the waters struggle together to get past the narrow place.

It is the same with the electricity flowing through the large copper wires-. It passes down one wire into the other, through the lamp in {silence.and darkness, so long as the rods touch and the path is clear. When the rods in the lamp are pulled apart, there is a space to be got over, an obstruction, like rocks in the bed of the brook. The electricity, like the water, struggles to get over the hindrance

in its patli, and it grows white hot with anger, and flames and hisses as it leaps across the narrow space between the rods. There is another kind of electric light, used in houses ; it has a smaller and softer light, steady,.white, and very beautiful. In these lamps, also, we have something like the narrow place in the brook. They are made with slender loops of carbon, inclosed in glass globes. The electricity, flowing silently, through a dark wire, enters the lamp, and finds only a narrow thread on which it can travel to reach the home-going wire, and in its struggle to get past, it heats the tiny thread of carbon to whiteness. Like a live coal, this slender thread gives us a mild, soft light, as long as the current flows. It seems calm and still, but it is enduring the same fury of the electricity that is shown in the larger lamps. This is the main idea on which these lamps are made : A stream of electricity is set flowing from a djmamo-electric machine through a wire until it meets a narrow place or a break in the wire. Ihen it seeks to get past the obstruction, and there is a grand putting forth of energy, and in this way the electric force, although itself invisible, is made known to our eyes by a beautiful light.— Si. Nicholas.