“You rascal!” roared the professor, and clenched his hand in passion, as if about to strike him. Ben Zoof laughed the more, and was on the point of repeating his satirical comments, when a stern order from the captain made him hold his tongue. The truth was that the professor was just as sensitive about his comet as the orderly was about Montmartre, and if the contention between the two had been allowed to go on unchecked, it is impossible to say what serious quarrel might not have arisen. When Professor Rosette’s equanimity had been restored, he said, “Thus, then, gentlemen, the diameter, the surface, the volume of my comet are settled; but there is more to be done. I shall not be satisfied until, by actual measurement, I have determined its mass, its density, and the force of gravity at its surface.” “A laborious problem,” remarked Count Timascheff. “Laborious or not, it has to be accomplished. I am resolved to find out what my comet weighs.” “Would it not be of some assistance, if we knew of what substance it is composed?” asked the lieutenant. “That is of no moment at all,” replied the professor; “the problem is independent of it.” “Then we await your orders,” was the captain’s reply. “You must understand, however,” said Rosette, “that there are various preliminary calculations to be made; you will have to wait till they are finished.” “As long as you please,” said the count. “No hurry at all,” observed the captain, who was not in the least impatient to continue his mathematical exercises. “Then, gentlemen,” said the astronomer, “with your leave we will for this purpose make an appointment a few weeks hence. What do you say to the 62d of April?” Without noticing the general smile which the novel date provoked, the astronomer left the hall, and retired to his observatory. CHAPTER V. WANTED: A STEELYARD Under the still diminishing influence of the sun’s attraction, but without let or hindrance, Gallia continued its interplanetary course, accompanied by Nerina, its captured satellite, which performed its fortnightly revolutions with unvarying regularity. Meanwhile, the question beyond all others important was ever recurring to the minds of Servadac and his two companions: were the astronomer’s calculations correct, and was there a sound foundation for his prediction that the comet would again touch the earth? But whatever might be their doubts or anxieties, they were fain to keep all their misgivings to themselves; the professor was of a temper far too cross-grained for them to venture to ask him to revise or re-examine the results of his observations.