IN A WORLD HALF AS LARGE. 685 



bation. Another consequence: we have just said that the cube 

 of the houses might be, on Mars, proportional to the cube of our 

 houses. But if boards of health should proceed there according to 

 the same principles as with us, they would have to order larger and 

 higher rooms. It may be suggested that the atmosphere of Mars is 

 less dense than ours, because it is not so thick, and gravity is less 

 there. Here is, indeed, a great difficulty, which, fortunately, it is 

 not necessary to resolve, because the law of Laplace supposes that 

 the density is the same at homologous points. On the surface of 

 Mars the air, then, has the same density and the same composition 

 as on the surface of the earth. But will the inspirations be as long? 

 The diaphragm of the Martians has not the same work to do as that 

 of the earth people. It is true that it is only half as thick, but its 

 surface is only a quarter, and the amplitude of its movement only one 

 half. But we must not discuss the rhythm of the diaphragm or the 

 beatings of the heart unless we shorten the days and increase the 

 number in a year. 



We see that whichever way we turn we can not for an instant 

 entertain the illusion that an earth-man could be put on Mars with- 

 out knowing it. 



We shall fall into more and more inextricable difficulties if we go 

 further into the detail of the respiratory and circulatory phenomena. 

 The capillary vessels of the Martians are four times narrower in sec- 

 tion. The heart, then, would have to use more force to make the 

 blood circulate; yet the heart is much weaker, with thinner walls, 

 smaller cavities, etc. Even if the Martians resemble men ex- 

 ternally, their whole interior organization must be decidedly very 

 different. 



The persistency will be remarked with which the number four 

 recurs in these calculations. This is because weight is reduced one 

 half on Mars, and also, because of the reduction in their linear dimen- 

 sions, the Martians have to exercise only half the effort to produce 

 the same apparent effect. It might be concluded from this that if 

 the universe was reduced geometrically in the proportion of three 

 or of five to one, we should immediately find ourselves nine or 

 twenty-five times lighter, stronger, and more active. By an inverse 

 conclusion, if we could imagine the case for a few moments, we 

 should have to be three or five times larger. Hence the paradoxical 

 conclusion that the smaller the world is, the larger its people should 

 be; so that, if the smallest asteroids are inhabited by men, the 

 inhabitants would be more important in size than their planet, 

 and might, in case of extremity, take it in their arms. On the 

 other hand, the larger the planetary mass, the smaller the men 

 should be, if their muscular sensations are comparable to ours. 



