“A fine sentence,” said Michel Ardan; “rather academical perhaps.”

“It follows,” resumed Barbicane, nowise put out, “that the visible face of the disc must be very agreeable to inhabit, as it is always lighted by the sun or the moon.”

“But,” said Nicholl, “this advantage must be quite compensated by the unbearable heat which this light must cause.”

“This inconvenience is the same under two faces, for the light reflected by the earth is evidently deprived of heat.  However, this invisible face is still more deprived of heat than the visible face.  I say that for you, Nicholl; Michel would probably not understand.”

“Thank you,” said Michel.

“In fact,” resumed Barbicane, “when the invisible face receives the solar light and heat the moon is new—­that is to say, that she is in conjunction, that she is situated between the sun and the earth.  She is then, on account of the situation which she occupies in opposition when she is full, nearer the sun by the double of her distance from the earth.  Now this distance may be estimated at the two-hundredth part of that which separates the sun and the earth; or, in round numbers, at two hundred thousand leagues.  Therefore this visible face is nearer the sun by two hundred thousand leagues when it receives his rays.”

“Quite right,” replied Nicholl.

“Whilst—­” resumed Barbicane.

“Allow me,” said Michel, interrupting his grave companion.

“What do you want?”

“I want to go on with the explanation.”

“Why?”

“To prove that I have understood.”

“Go on, then,” said Barbicane, smiling.

“Whilst,” said Michel, imitating the tone and gestures of President Barbicane, “when the visible face of the moon is lighted by the sun the moon is full—­that is to say, situated with regard to the earth the opposite to the sun.  The distance which separates it from the radiant orb is then increased in round numbers by 200,000 leagues, and the heat which it receives must be rather less.”

“Well done!” exclaimed Barbicane.  “Do you know, Michel, for an artist you are intelligent.”

“Yes,” answered Michel carelessly, “we are all intelligent on the Boulevard des Italiens.”

Barbicane shook hands gravely with his amiable companion, and went on enumerating the few advantages reserved to the inhabitants of the visible face.

Amongst others he quoted the observations of the sun’s eclipses, which can only be seen from one side of the lunar disc, because the moon must be in opposition before they can take place.  These eclipses, caused by the interposition of the earth between the sun and the moon, may last two hours, during which, on account of the rays refracted by its atmosphere, the terrestrial globe can only appear like a black spot upon the sun.

“Then,” said Nicholl, “the invisible hemisphere is very ill-treated by Nature.”