“Certainly; but without explaining the origin of these luminous points.  Herschel himself did not thereby conclude the necessity of a lunar atmosphere.”

“Well answered,” said Michel Ardan, complimenting his adversary; “I see that you are well up in selenography.”

“Yes, sir; and I may add that the most skilful observers, MM.  Boeer and Moedler, agree that air is absolutely wanting on the moon’s surface.”

A movement took place amongst the audience, who appeared struck by the arguments of this singular personage.

“We will pass on again,” answered Michel Ardan, with the greatest calmness, “and arrive now at an important fact.  A skilful French astronomer, M. Laussedat, whilst observing the eclipse of July 18th, 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 fact authenticated?”

“It is absolutely certain.”

An inverse movement brought back the audience to the side of their favourite hero, whose adversary remained silent.

Ardan went on speaking without showing any vanity about his last advantage; he said simply—­

“You see, therefore, my dear sir, that it cannot be positively affirmed that there is no atmosphere on the surface of the moon.  This atmosphere is probably not dense, but science now generally admits that it exists.”

“Not upon the mountains,” replied the unknown, who would not give in.

“No, but in the depths of the valleys, and it is not more than some hundreds of feet deep.”

“Any way you will do well to take your precautions, for the air will be terribly rarefied.”

“Oh, there will always be enough for one man.  Besides, once delivered up there, I shall do my best to economise it and only to breathe it on great occasions.”

A formidable burst of laughter saluted the mysterious interlocutor, who looked round the assembly daring it proudly.

“Then,” resumed Michel Ardan, carelessly, “as we are agreed upon the presence of some atmosphere, we are forced to admit the presence of some water—­a consequence I am delighted with, for my part.  Besides, I have another observation to make.  We only know one side of the moon’s disc, and if there is little air on that side there may be much on the other.”

“How so?”

“Because the moon under the action of terrestrial attraction has assumed the form of an egg, of which we see the small end.  Hence the consequence due to the calculations of Hausen, that its centre of gravity is situated in the other hemisphere.  Hence this conclusion that all the masses of air and water have been drawn to the other side of our satellite in the first days of the creation.”

“Pure fancies,” exclaimed the unknown.