680 POPULAR SCIENCE MONTHLY. 



tern, 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 multi- 

 plied 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 rais- 

 ing 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 dimin- 

 ished one half; so that the work to be performed is reduced to one 

 thirty-second. On the other hand, his strength, which is propor- 

 tioned 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 un- 

 usually 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 down- 

 stairs. 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 vol- 

 ume, or to one eighth, but his weight is reduced to a sixteenth, and he 

 only has to lift it half as high. 



