Next to its usefulness for heating and cooking, the greatest use of fire is to furnish light to drive away darkness. Man is not content, like birds and brutes, to go to sleep at the setting of the sun. He takes a part of the night-time and uses it for work or for travel or for social pleasures, or for the improvement of his mind, and in this way adds several years to life. He could not do this if he were compelled to grope in darkness. When the great source of daylight disappears he must make light for himself, for the sources of night-light--the moon and stars and aurora borealis and lightning--are not sufficient to satisfy his wants. In this chapter we shall follow man in his efforts to conquer darkness, and we shall have the story of the lamp. We may begin the story with an odd but interesting kind of lamp. The firefly or lightning-bug which we see so often in the summer nights was in the earliest time brought into service and made to shed its light for man. Fireflies were imprisoned in a rude box--in the shell of a cocoanut, perhaps, or in a gourd--and the light of their bodies was allowed to shoot out through the numerous holes made in the box. We must not despise the light given out by these tiny creatures. "In the mountains of Tijuca," says a traveler, "I have read the finest print by the light of one of these natural lamps (fireflies) placed under a common glass tumbler (Fig. 1), and with distinctness I could tell the hour of the night and discern the very small figures which marked the seconds of a little Swiss watch." [Illustration: FIG. 1.--A FIREFLY LAMP.] [Illustration: FIG. 2.--A BURNING STICK WAS THE FIRST LAMP.] Although fireflies have been used here and there by primitive folk, they could hardly have been the first lamp. Man's battle with darkness really began with the _torch_, which was lighted at the fire in the cave or in the wigwam and kept burning for purposes of illumination. A burning stick was the first lamp (Fig. 2). The first improvement in the torch was made when slivers or splinters of resinous or oily wood were tied together and burned. We may regard this as a lamp which is all wick. This invention resulted in a fuller and clearer light, and one that would burn longer than the single stick. A further improvement came when a long piece of wax or fatty substance was wrapped about with leaves. This was something like a candle, only the wick (the leaves) was outside, and the oily substance which fed the wick was in the center.