“A twelvemonth! Not a Gallian twelvemonth?” exclaimed Rosette.

Servadac looked bewildered. Lieutenant Procope could not suppress a smile.

“What are you laughing at?” demanded the professor, turning round upon him angrily.

“Nothing, sir; only it amuses me to see how you want to revise the terrestrial calendar.”

“I want to be logical, that’s all.”

“By all manner of means, my dear professor, let us be logical.”

“Well, then, listen to me,” resumed the professor, stiffly. “I presume you are taking it for granted that the Gallian year—by which I mean the time in which Gallia makes one revolution round the sun—is equal in length to two terrestrial years.”

They signified their assent.

“And that year, like every other year, ought to be divided into twelve months.”

“Yes, certainly, if you wish it,” said the captain, acquiescing.