CHAPTER VIII.GALLIA WEIGHED.
A QUARTER of an hour later, the visitors to the Hansa had
re-assembled 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 been 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 metre 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 metre.”[1]
Ben Zoof looked on in perplexity, regarding the
lecturer with much the same curiosity as he would have
watched the performances of a travelling 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
calibre or diameter of each piece of money is rigourously
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 millimetres[2]
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 millimetres that make up the terrestrial metre.
They had conjectured rightly. From the pile of forty
five-franc pieces. Rosette took ten and spread them out
lengthwise in a row upon the table; to these he added
the ten two-franc pieces and the twenty fifty-centimes.
“Now, gentlemen,” he said, “here we have the measure
of a metre exactly.”
And, taking a scrap of paper, he put down rapidly a
few figures, which he handed round for general inspection.
The little calculation was simple enough:—

10 5-franc
pieces, each
37
millimetres in
diameter
=
.37
metre.

10 2-franc
"
27
"
"
=
.27
"

30 50-centime
"
18
"
"
=
.36
"

Total ...
...

1.00
metre.

“I understand perfectly,” said Servadac, when he had
examined the paper; “the straight line drawn through the
centres of these coins represents a terrestrial metre.”
“Precisely,” replied the professor.
“Dear me!” exclaimed Ben Zoof, in astonishment,
“what a thing it is to be learned!”
“Not much learning wanted for that!” said the professor,
shrugging his shoulders contemptuously, as he
made his marks on the table corresponding to the extremities
of the line of money.
The measurement thus obtained was by means of a
pair of compasses divided accurately into ten equal
portions, or decimetres, 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 decimetre 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 kilogramme.[3]
“Oh!” cried Ben Zoof; “to be able to do all this I
say 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 decimetre
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.”
Every one gave him their 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.[4]
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 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 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 decimetre; 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 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 decimetre. 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 labour.
Since a cubic decimetre of the hard substance of Gallia
would weigh ten kilogrammes upon the earth, Gallia would
weigh as many times ten kilogrammes as there were cubic
decimetres in its volume. This volume was already known
to be 211,432,460 cubic kilometres (i.e. 47,880,000 cubic
miles) or 211,432,460 millions of millions of cubic decimetres—a
number expressed by 21 digits—and these would
represent the number of kilogrammes in the mass of
Gallia, which consequently weighed 4,788,566,540 millions
of millions of kilogrammes less than the earth.
“And do you know how much the earth weighs?”[5]
inquired Ben Zoof, almost losing his breath at these
stupendous calculations.
“If I were to tell you, wiseacre, I do not suppose you
would be much the wiser. Have you any idea of what is
meant by a thousand millions?”
“Not much, I confess,” said Ben Zoof.
“Well, then, if you owed a thousand million francs,
eighteen or nineteen centuries ago, at the beginning of the
Christian era, and had been paying a franc a minute ever
since, you would not have got out of debt yet.”
“No, that I shouldn't,” answered the orderly; “a
quarter of an hour of that fun would have ruined me. But
really,” he added, “I should like to hear how much the
earth weighs.”
“Five millions, eight hundred and seventy-five
thousand trillions of kilogrammes—a number which is
formed of twenty-six[6] figures,” said Lieutenant Procope.
“And the moon?”
“Seventy thousand trillions of kilogrammes.”
“And the sun?” Ben Zoof went on.
“Two quintillions of kilogrammes—thirty-one figures,”
answered the professor.
“Ay,” said Ben Zoof, “I dare say you are right within
a quarter of a gramme.”
The professor frowned and looked angry, but the
captain diverted him by making a remark about the
diminished force of gravity.
“Yes,” said Rosette; “our muscular force is seven times
as great as it was. A man who used to be able to carry
a couple of hundred-weight can here carry fourteen.”
“I suppose that accounts for our being able to jump so
high,” observed Ben Zoof.
“And if Gallia had been lighter, Ben Zoof, you would
have been able to jump higher still,” the lieutenant said.
“Ay, perhaps even over Montmartre,” added the
professor, with a malicious twinkle in his eye.
The orderly winced under the retaliation.
“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 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 terrestial kilogramme would weigh 28 kilogrammes.”
“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 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 Mont,
martre 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 the count.
“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 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.”

1^  A metre = 39.371 inches.
2^  A millimetre = .03937 inches.
3^  

Appended is a table of the weights of various French coins:—

In gold:
100
francs
weigh
32.25
grammes.

50
"
"
16.12
"

20
"
"
6.45
"

10
"
"
3.22
"

In silver:
5
"
"
25.00
"

2
"
"
10.00
"

1
"
"
5.00
"

.5
"
"
2.50
"

In copper:
.1
"
"
10.00
"

.05
"
"
5.00
"

.02
"
"
2.00
"

.01
"
"
1.00
"

4^ 
On this subject an amusing anecdote is related by the illustrious
astronomer himself. One day, just after he had been alluding to this as his
usual habit, a young man entered the room, and feeling sure the lecturer knew
him well, saluted him accordingly. “I regret, I have not the pleasure of your
acquaintance,” said M. Arago. “Then surprise me,” replied the young
student: “not only am I most regular in my attendance at your lectures, but
you never take your eyes off me from the beginning to the end.”
5^  The earth's
weight is estimated at 6,000,000,000,000,000,000,000 tons.
6^  Translation error. Verne: vingt-cinq chiffres,
twenty-five figures.