planet, or rather between its inhabitants 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 anything 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 Bréant prize an annual 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 constitution 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 possessed 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 possibility 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 industrious authors of the lunar maps, the Beers, Mädlers, 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 negative 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 interastral telegraphy. At its most favorable oppositions, Mars is still 42,000,000 miles from us, or a hundred and sixty times farther than the moon; while the diameter of its disk is only 25″. According 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
