Off on a Comet

by Jules Verne

Book II - Chapter VII - Gallia Weighed

A QUARTER of an hour later, the visitors to the Hansa had reassembled in the common hall of Nina's Hive.

"Now, gentlemen, we can proceed," said the professor. "May I request that this table may be cleared?"

Ben Zoof removed the various articles that were lying on the table, and the coins which had just been borrowed from the Jew were placed upon it in three piles, according to their value.

The professor commenced. "Since none of you gentlemen, at the time of the shock, took the precaution to save either a meter measure or a kilogram weight from the earth, and since both these articles are necessary for the calculation on which we are engaged, I have been obliged to devise means of my own to replace them."

This exordium delivered, he paused and seemed to watch its effect upon his audience. But they were too well acquainted with the professor's temper to make any attempt to exonerate themselves from the rebuke of carelessness, and submitted silently to the implied reproach.

"I have taken pains," he continued, "to satisfy myself that these coins are in proper condition for my purpose. I find them unworn and unchipped; indeed, they are almost new. They have been hoarded instead of circulated; accordingly, they are fit to be utilized for my purpose of obtaining the precise length of a terrestrial meter."

Ben Zoof looked on in perplexity, regarding the lecturer with much the same curiosity as he would have watched the performances of a traveling mountebank at a fair in Montmartre; but Servadac and his two friends had already divined the professor's meaning. They knew that French coinage is all decimal, the franc being the standard of which the other coins, whether gold, silver, or copper, are multiples or measures; they knew, too, that the caliber or diameter of each piece of money is rigorously determined by law, and that the diameters of the silver coins representing five francs, two francs, and fifty centimes measure thirty-seven, twenty-seven, and eighteen millimeters respectively; and they accordingly guessed that Professor Rosette had conceived the plan of placing such a number of these coins in juxtaposition that the length of their united diameters should measure exactly the thousand millimeters that make up the terrestrial meter.

The measurement thus obtained was made by means of a pair of compasses divided accurately into ten equal portions, or decimeters, each of course 3.93 inches long. A rod was then cut of this exact length and given to the engineer of the Dobryna, who was directed to cut out of the solid rock the cubic decimeter required by the professor.

The next business was to obtain the precise weight of a kilogram. This was by no means a difficult matter. Not only the diameters, but also the weights, of the French coins are rigidly determined by law, and as the silver five-franc pieces always weigh exactly twenty-five grams, the united weight of forty of these coins is known to amount to one kilogram.

"Oh!" cried Ben Zoof: "to be able to do all this, I see you must be rich as well as learned."

With a good-natured laugh at the orderly's remark, the meeting adjourned for a few hours. By the appointed time the engineer had finished his task, and with all due care had prepared a cubic decimeter of the material of the comet.

"Now, gentlemen," said Professor Rosette, "we are in a position to complete our calculation; we can now arrive at Gallia's attraction, density, and mass."

Everyone gave him complete attention.

"Before I proceed," he resumed, "I must recall to your minds Newton's general law, 'that the attraction of two bodies is directly proportional to the product of their masses, and inversely proportional to the square of their distances."

"Yes," said Servadac; "we remember that."

"Well, then," continued the professor, "keep it in mind for a few minutes now. Look here! In this bag are forty five-franc pieces—altogether they weigh exactly a kilogram; by which I mean if we were on the earth, and if I were to hang the bag on the hook of the steelyard, the indicator on the dial would register one kilogram. This is clear enough, I suppose?"

As he spoke the professor designedly kept his eyes fixed upon Ben Zoof. He was avowedly following the example of Arago, who was accustomed always in lecturing to watch the countenance of the least intelligent of his audience, and when he felt that he had made his meaning clear to him, he concluded that he must have succeeded with all the rest. In this case, however, it was technical ignorance, rather than any lack of intelligence, that justified the selection of the orderly for this special attention.

Satisfied with his scrutiny of Ben Zoof's face, the professor went on. "And now, gentlemen, we have to see what these coins weigh here upon Gallia."

He suspended the money bag to the hook; the needle oscillated, and stopped. "Read it off!" he said.

The weight registered was one hundred and thirty-three grams. "There, gentlemen, one hundred and thirty-three grams! Less than one-seventh of a kilogram! You see, consequently, that the force of gravity here on Gallia is not one-seventh of what it is upon the earth!"

"Interesting!" cried Servadac, "most interesting! But let us go and compute the mass."

"No, captain, the density first," said Rosette.

"Certainly," said the lieutenant; "for as we already know the volume, we can determine the mass as soon as we have ascertained the density."

The professor took up the cube of rock. "You know what this is," he went on to say. "You know, gentlemen, that this block is a cube hewn from the substance of which everywhere, all throughout your voyage of circumnavigation, you found Gallia to be composed—a substance to which your geological attainments did not suffice to assign a name."

"Our curiosity will be gratified," said Servadac, "if you will enlighten our ignorance."

But Rosette did not take the slightest notice of the interruption.

"A substance it is which no doubt constitutes the sole material of the comet, extending from its surface to its innermost depths. The probability is that it would be so; your experience confirms that probability: you have found no trace of any other substance. Of this rock here is a solid decimeter; let us get at its weight, and we shall have the key which will unlock the problem of the whole weight of Gallia. We have demonstrated that the force of attraction here is only one-seventh of what it is upon the earth, and shall consequently have to multiply the apparent weight of our cube by seven, in order to ascertain its proper weight. Do you understand me, goggle-eyes?"

This was addressed to Ben Zoof, who was staring hard at him. "No!" said Ben Zoof.

"I thought not; it is of no use waiting for your puzzle-brains to make it out. I must talk to those who can understand."

The professor took the cube, and, on attaching it to the hook of the steelyard, found that its apparent weight was one kilogram and four hundred and thirty grams.

"Here it is, gentlemen; one kilogram, four hundred and thirty grams. Multiply that by seven; the product is, as nearly as possible, ten kilograms. What, therefore, is our conclusion? Why, that the density of Gallia is just about double the density of the earth, which we know is only five kilograms to a cubic decimeter. Had it not been for this greater density, the attraction of Gallia would only have been one-fifteenth instead of one-seventh of the terrestrial attraction."

The professor could not refrain from exhibiting his gratification that, however inferior in volume, in density, at least, his comet had the advantage over the earth.

Nothing further now remained than to apply the investigations thus finished to the determining of the mass or weight. This was a matter of little labor.

"Let me see," said the captain; "what is the force of gravity upon the various planets?"

"You can't mean, Servadac, that you have forgotten that? But you always were a disappointing pupil."

The captain could not help himself: he was forced to confess that his memory had failed him.

"Well, then," said the professor, "I must remind you. Taking the attraction of the earth as 1, that on Mercury is 1.15, on Venus it is .92, on Mars .5, and on Jupiter 2.45; on the moon the attraction is .16, whilst on the surface of the sun a terrestrial kilogram would weigh 28 kilograms."

"Therefore, if a man upon the surface of the sun were to fall down, he would have considerable difficulty in getting up again. A cannon ball, too, would only fly a few yards," said Lieutenant Procope.

"A jolly battle-field for cowards!" exclaimed Ben Zoof.

"Not so jolly, Ben Zoof, as you fancy," said his master; "the cowards would be too heavy to run away."

Ben Zoof ventured the remark that, as the smallness of Gallia secured to its inhabitants such an increase of strength and agility, he was almost sorry that it was not a little smaller still.

"Though it could not have been very much smaller anyhow," he added, looking slyly at the professor.

"Idiot!" exclaimed Rosette. "Your head is too light already; a puff of wind would blow it away."

"I must take care of my head, then, and hold it on," replied the irrepressible orderly.

Unable to get the last word, the professor was about to retire, when Servadac detained him.

"Permit me to ask you one more question," he said. "Can you tell me what is the nature of the soil of Gallia?"

"Yes, I can answer that. And in this matter I do not think your impertinent orderly will venture to put Montmartre in the comparison. This soil is of a substance not unknown upon the earth." And speaking very slowly, the professor said: "It contains 70 per cent. of tellurium, and 30 per cent. of gold."

Servadac uttered an exclamation of surprise.

"And the average of the specific gravities of these two substances is 10, precisely the number that represents Gallia's density."

"A comet of gold"!" ejaculated the captain.

"Yes; a realization of what the illustrious Maupertuis has already deemed probable," replied the astronomer.

"If Gallia, then, should ever become attached to the earth, might it not bring about an important revolution in all monetary affairs?" inquired the count.

"No doubt about it!" said Rosette, with manifest satisfaction. "It would supply the world with about 246,000 trillions of francs."

"If would make gold about as cheap as dirt, I suppose," said Servadac.

The last observation, however, was entirely lost upon the professor, who had left the hall with an air almost majestic, and was already on his way to the observatory.

"And what, I wonder, is the use of all these big figures?" said Ben Zoof to his master, when next day they were alone together.

"That's just the charm of them, my good fellow," was the captain's cool reply, "that they are of no use whatever."