I had only just time to replace the unfortunate document upon the table.
Professor Liedenbrock seemed to be greatly abstracted.
The ruling thought gave him no rest. Evidently he had gone deeply into the matter, analytically and with profound scrutiny. He had brought all the resources of his mind to bear upon it during his walk, and he had come back to apply some new combination.
He sat in his armchair, and pen in hand he began what looked very much like algebraic formula: I followed with my eyes his trembling hands, I took count of every movement. Might not some unhoped-for result come of it? I trembled, too, very unnecessarily, since the true key was in my hands, and no other would open the secret.
For three long hours my uncle worked on without a word, without lifting his head; rubbing out, beginning again, then rubbing out again, and so on a hundred times.
I knew very well that if he succeeded in setting down these letters in every possible relative position, the sentence would come out. But I knew also that twenty letters alone could form two quintillions, four hundred and thirty-two quadrillions, nine hundred and two trillions, eight billions, a hundred and seventy-six millions, six hundred and forty thousand combinations. Now, here were a hundred and thirty-two letters in this sentence, and these hundred and thirty-two letters would give a number of different sentences, each made up of at least a hundred and thirty-three figures, a number which passed far beyond all calculation or conception.
So I felt reassured as far as regarded this heroic method of solving the difficulty.
But time was passing away; night came on; the street noises ceased; my uncle, bending over his task, noticed nothing, not even Martha half opening the door; he heard not a sound, not even that excellent woman saying:
"Will not monsieur take any supper to-night?"
And poor Martha had to go away unanswered. As for me, after long resistance, I was overcome by sleep, and fell off at the end of the sofa, while uncle Liedenbrock went on calculating and rubbing out his calculations.
When I awoke next morning that indefatigable worker was still at his post. His red eyes, his pale complexion, his hair tangled between his feverish fingers, the red spots on his cheeks, revealed his desperate struggle with impossibilities, and the weariness of spirit, the mental wrestlings he must have undergone all through that unhappy night.
To tell the plain truth, I pitied him. In spite of the reproaches which I considered I had a right to lay upon him, a certain feeling of compassion was beginning to gain upon me. The poor man was so entirely taken up with his one idea that he had even forgotten how to get angry. All the strength of his feelings was concentrated upon one point alone; and as their usual vent was closed, it was to be feared lest extreme tension should give rise to an explosion sooner or later.
I might with a word have loosened the screw of the steel vice that was crushing his brain; but that word I would not speak.
Yet I was not an ill-natured fellow. Why was I dumb at such a crisis? Why so insensible to my uncle's interests?
"No, no," I repeated, "I shall not speak. He would insist upon going; nothing on earth could stop him. His imagination is a volcano, and to do that which other geologists have never done he would risk his life. I will preserve silence. I will keep the secret which mere chance has revealed to me. To discover it, would be to kill Professor Liedenbrock! Let him find it out himself if he can. I will never have it laid to my door that I led him to his destruction."
Having formed this resolution, I folded my arms and waited. But I had not reckoned upon one little incident which turned up a few hours after.
When our good Martha wanted to go to Market, she found the door locked. The big key was gone. Who could have taken it out? Assuredly, it was my uncle, when he returned the night before from his hurried walk.
Was this done on purpose? Or was it a mistake? Did he want to reduce us by famine? This seemed like going rather too far! What! should Martha and I be victims of a position of things in which we had not the smallest interest? It was a fact that a few years before this, whilst my uncle was working at his great classification of minerals, he was forty-eight hours without eating, and all his household were obliged to share in this scientific fast. As for me, what I remember is, that I got severe cramps in my stomach, which hardly suited the constitution of a hungry, growing lad.
Now it appeared to me as if breakfast was going to be wanting, just as supper had been the night before. Yet I resolved to be a hero, and not to be conquered by the pangs of hunger. Martha took it very seriously, and, poor woman, was very much distressed. As for me, the impossibility of leaving the house distressed me a good deal more, and for a very good reason. A caged lover's feelings may easily be imagined.
My uncle went on working, his imagination went off rambling into the ideal world of combinations; he was far away from earth, and really far away from earthly wants.
About noon hunger began to stimulate me severely. Martha had, without thinking any harm, cleared out the larder the night before, so that now there was nothing left in the house. Still I held out; I made it a point of honour.
Two o'clock struck. This was becoming ridiculous; worse than that, unbearable. I began to say to myself that I was exaggerating the importance of the document; that my uncle would surely not believe in it, that he would set it down as a mere puzzle; that if it came to the worst, we should lay violent hands on him and keep him at home if he thought on venturing on the expedition that, after all, he might himself discover the key of the cipher, and that then I should be clear at the mere expense of my involuntary abstinence.
These reasons seemed excellent to me, though on the night before I should have rejected them with indignation; I even went so far as to condemn myself for my absurdity in having waited so long, and I finally resolved to let it all out.
I was therefore meditating a proper introduction to the matter, so as not to seem too abrupt, when the Professor jumped up, clapped on his hat, and prepared to go out.
Surely he was not going out, to shut us in again! no, never!
"Uncle!" I cried.
He seemed not to hear me.
"Uncle Liedenbrock!" I cried, lifting up my voice.
"Ay," he answered like a man suddenly waking.
"Uncle, that key!"
"What key? The door key?"
"No, no!" I cried. "The key of the document."
The Professor stared at me over his spectacles; no doubt he saw something unusual in the expression of my countenance; for he laid hold of my arm, and speechlessly questioned me with his eyes. Yes, never was a question more forcibly put.
I nodded my head up and down.
He shook his pityingly, as if he was dealing with a lunatic. I gave a more affirmative gesture.
His eyes glistened and sparkled with live fire, his hand was shaken threateningly.
This mute conversation at such a momentous crisis would have riveted the attention of the most indifferent. And the fact really was that I dared not speak now, so intense was the excitement for fear lest my uncle should smother me in his first joyful embraces. But he became so urgent that I was at last compelled to answer.
"Yes, that key, chance--"
"What is that you are saying?" he shouted with indescribable emotion.
"There, read that!" I said, presenting a sheet of paper on which I had written.
"But there is nothing in this," he answered, crumpling up the paper.
"No, nothing until you proceed to read from the end to the beginning."
I had not finished my sentence when the Professor broke out into a cry, nay, a roar. A new revelation burst in upon him. He was transformed!
"Aha, clever Saknussemm!" he cried. "You had first written out your sentence the wrong way."
And darting upon the paper, with eyes bedimmed, and voice choked with emotion, he read the whole document from the last letter to the first.
It was conceived in the following terms:
In Sneffels Joculis craterem quem delibat Umbra Scartaris Julii intra calendas descende, Audax viator, et terrestre centrum attinges. Quod feci, Arne Saknussemm. 
Which bad Latin may be translated thus:
"Descend, bold traveller, into the crater of the jokul of Sneffels, which the shadow of Scartaris touches before the kalends of July, and you will attain the centre of the earth; which I have done, Arne Saknussemm."
In reading this, my uncle gave a spring as if he had touched a Leyden jar. His audacity, his joy, and his convictions were magnificent to behold. He came and he went; he seized his head between both his hands; he pushed the chairs out of their places, he piled up his books; incredible as it may seem, he rattled his precious nodules of flints together; he sent a kick here, a thump there. At last his nerves calmed down, and like a man exhausted by too lavish an expenditure of vital power, he sank back exhausted into his armchair.
"What o'clock is it?" he asked after a few moments of silence.
"Three o'clock," I replied.
"Is it really? The dinner-hour is past, and I did not know it. I am half dead with hunger. Come on, and after dinner--"
 In the cipher, AUDAX is written AVDAS, and QUOD and QUEM, HOD and KEN. (Tr.)
"After dinner, pack up my trunk."
"What?" I cried.
"And yours!" replied the indefatigable Professor, entering the dining-room.