362 THE POPULAR SCIENCE MONTHLY. 



planet, or rather between its inliabitants and the inhabitants of a 

 planet, would be something to sharpen the curiosity of the whole 

 world. I do not see that astronomy or mankind would gain any- 

 thing by it, but what conjectures, what paradoxes, what high 

 fancies, we should enjoy if it were carried out ! 



The Academy is said to be disposed to accept the legacy, by 

 virtue of a clause like that which makes the Brdant prize an an- 

 nual recompense allotted to the authors of discoveries tending to 

 advance the solution of the problem of a cure for cholera. In the 

 same way, the income of the capital bequeathed by Madame 

 Guzman will work in favor of investigations relating to the con- 

 stitution of the heavenly bodies. I do not think I am hazarding 

 much when I assert that it will be a long while before the new 

 prize is awarded, in its totality at least. But this was doubtless 

 not the opinion of the testatrix. Without going deeply into the 

 question — for that would require a long discussion — the probable 

 correctness of my prediction can be shown in a few lines. 



To any one well acquainted with the present knowledge pos- 

 sessed by astronomers concerning the physical aspect of the stars 

 of our system, it is evident that only two of the planets are in a 

 condition to encourage the hopes of those who believe in the pos- 

 sibility of interplanetary communications, to wit, the moon and 

 Mars — the moon especially. Its small distance of 240,000 miles, 

 the clearness of its disk, the facility with which minor features 

 can be distinguished upon it with the telescope, the absence of all 

 cloudiness that can conceal spots upon it, make our satellite an 

 eminently fitting body to which to send signals from the earth. 

 We must believe that the inhabitants of the moon have not 

 thought of this, or the numerous observers of its disk, the indus- 

 trious authors of the lunar maps, the Beers, Madlers, Schmidts, 

 at least, would have perceived the signals. But stop. Are there, 

 can there be, inhabitants in the moon, where air and water are 

 absent ? If there is any point generally admitted, it is the nega- 

 tive of this question. 



Under these conditions, it seems idle for us of the earth to 

 trouble ourselves about means of answering the inhabitants of 

 the moon, or of ourselves provoking signals thence ; and this is 

 a pity, for the second heavenly body to be questioned, the planet 

 Mars, is infinitely less favorable for the establishment of an inter- 

 astral telegraphy. At its most favorable oppositions, Mars is still 

 43,000,000 miles from us, or a hundred and sixty times farther 

 than the moon ; while the diameter of its disk is only 25". Ac- 

 cording to Schiaparelli, the smallest objects visible on its surface 

 under the most favorable circumstances — such as a bright spot on 

 a dark ground, or a dark spot on a bright ground — must have a 

 diameter equal to a fiftieth part of that of the planet, or about 



