Page:Popular Science Monthly Volume 52.djvu/700

680, which is brought out in the above, arises from the fact that capacity is a thing of three dimensions, while weight has four. Mass, being for the same density proportional to the volume, has, in kind, only three dimensions; but weight has four, because it is mass multiplied by a new factor, gravity, which is not the same on our Mars as on the earth. Some extremely curious consequences have their origin in this fact.

Megamicros, as we shall call our man of the earth transported in his sleep to the new Mars, wakes up, opens his eyes, and finds himself in bed in his room. All the things in it are familiar to him—the furniture, clothes, books, and wares are just where he had left them overnight. He does not suspect the trick that has been played on him. He stretches himself, throws up his arms, leaps from his bed, goes to the washstand, lifts the pitcher, puts on his clothes—and is greatly surprised.

All these actions are of a common character, and consist in raising masses to a certain height. His water pitcher, for instance, holds two litres, new measure. On the earth these two litres, representing two kilogrammes, require a certain effort to be raised, say, to the height of thirty centimetres. But on Mars these two litres weigh only two Martian kilogrammes, or sixteen times less in earthly weight. Further, he does not have to lift them to a height of thirty centimetres, but of only fifteen centimetres, his size being diminished one half; so that the work to be performed is reduced to one thirty-second. On the other hand, his strength, which is proportioned to the volume or the mass of his muscles, is only reduced to one eighth. Consequently, the effort he is required to make is four times less. His water pitcher seems extremely light; so do his clothes. He probably remarked the same thing when he threw up his arms and jumped from his bed, but simply thought he was in unusually good spirits.

If he is in the habit of practicing in gymnastics, and if, on the earth, he raised weights of fifty kilogrammes above his head, he is no little astonished to see that he can now play with weights four times as heavy, or of two hundred kilogrammes.

He prepares to go out. He walks across the length and breadth of his room. There is nothing unusual. The room is smaller, indeed, but his steps are correspondingly shorter. He goes downstairs. He feels again a wonderful lightness and spring. He hardly has to touch the steps. When he goes upstairs his astonishment increases, if that is possible, for he can go up four steps at a time. His muscular energy, it is true, is reduced in proportion to his volume, or to one eighth, but his weight is reduced to a sixteenth, and he only has to lift it half as high.