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of necessity burned to keep up the supply of steam.
From this you will see that there is a close relationship between the incandescent light and your grate fire; the former being the energy of the latter in a form almost identically the same, in both instances we have incandescent carbon, the ultimate object in one case being heat, and in the other light.
Having proceeded thus far, let us glance back over the road by which we have come and see that we fully comprehend the relation, each to the other, of the several devices necessary for the creation and utilization of the electric current for the purpose of lighting by incandescence,
Strictly speaking we should start at the coal pile; but were we to whittle our stick to so fine a point we might be tempted to go back beyond the glacial period, when our coal fields existed as the superabundant vegetation of a tropical clime. It will, however, suffice us to confine ourselves to this age of Light;
