Part of: BOOK II
From: Off On A Comet
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 kilogramme 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, who, however, 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 by means of a pair of compasses
divided accurately into ten equal portions, or decimeters, each of
course 3.93 inches long. A lath 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 kilogramme. 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 grammes,
the united weight of forty of these coins is known to amount to one
"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 his 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 kilogramme; by which I mean that
if we were on the earth, and I were to hang the bag on the hook of the
steelyard, the indicator on the dial would register one kilogramme. 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
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
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 grammes.
"There, gentlemen, one hundred and thirty-three grammes! Less than
one-seventh of a kilogramme! 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 on 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
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
"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 kilogramme and four
hundred and thirty grammes.
"Here it is, gentlemen; one kilogramme, four hundred and thirty grammes.
Multiply that by seven; the product is, as nearly as possible, ten
kilogrammes. 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 kilogrammes 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
"Let me see," said the captain; "what is the force of gravity upon the
"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 on 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 kilogramme would weigh 28
"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 had not been a little smaller still.
"Though it could not anyhow have been very much smaller," 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
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 into 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 sum 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
"No doubt about it!" said Rosette, with manifest satisfaction. "It would
supply the world with about 246,000 trillions of francs."
"It 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."
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