"True! but, as they furnished themselves the oxygen necessary for combustion, the mere fact of their eruption does not prove the presence of an atmosphere."
"Proceed again, then; and let us set aside this class of arguments in order to come to direct observations. In 1715 the astronomers Louville and Halley, watching the eclipse of the 3rd May, remarked some very extraordinary scintillations. These jets of light, rapid in nature, and of frequent recurrence, they attributed to thunderstorms generated in the lunar atmosphere."
"In 1715," replied the unknown, "the astronomers Louville and Halley mistook for lunar phenomena some which were purely terrestrial, such as meteoric or other bodies which are generated in our own atmosphere. This was the scientific explanation at the time of the facts; and that is my answer now."
"On again, then," replied Ardan; "Herschel, in 1787, observed a great number of luminous points on the moon's surface, did he not?"
"Yes! but without offering any solution of them. Herschel himself never inferred from them the necessity of a lunar atmosphere. And I may add that Bœer and Moedler, the two great authorities upon the moon, are quite agreed as to the entire absence of air on its surface."
A movement was here manifest among the assemblage, who appeared to be growing excited by the arguments of this singular personage.
"Let us proceed," replied Ardan, with perfect coolness, "and come to one important fact. A skilful French astronomer, M. Laussedat, in watching the eclipse of July 18, 1860, proved that the horns of the solar crescent were rounded and truncated. Now, this appearance could only have been produced by a deviation of the solar rays in traversing the atmosphere of the moon. There is no other possible explanation of the fact."
"But is this established as a fact?"
"Absolutely certain!"
A counter-movement here took place in favour of the hero of the meeting, whose opponent was now reduced to silence. Ardan resumed the conversation; and without exhibiting any exultation at the advantage he had gained, simply said,—