like a gentleman, but that now lie was obliged to work for his living." But he was mistaken in thinking that the sun had ever the life of a gentleman. He has always worked as a slave, nay, he has been always the slave of slaves. He has really done all the work, while men and their machines have taken all the credit to themselves. They have only directed the work, while all the power has been supplied by the sun. We speak of the marvellous power of the steam-engine; but to what does it owe its power? The answer is, the elasticity of steam. But how is this elasticity accounted for? The answer is equally ready, that the heat of the furnace has produced it. But the circle of causation is not yet complete. From what source has the coal derived its heat? Till lately the answer would be held satisfactory, that the coal is fossil wood, and therefore it produces heat by burning. But we must now wring from nature the secret of this possession of heat and power by coal. The answer of science is, that the coal is merely a receptacle for the heat and light of the sun. The sun's energy is bottled up, as it were, in the coal, and the burning of it is the uncorking of the bottle. It may be said that this is only a play upon words, as it is a mere truism to hold that a tree could not grow without the influence of the sun, and that there could be no coal without trees; but that this does not imply that the heat of the coal is the very heat of the sun. Now, what we wish to impress is, that the
