"John and I will take general charge of the machinery in that room, and he will also look after your machines whilst you are with me in our Martian air-chamber. In addition to these arrangements, we have prepared a concentrated air of the same kind which we can carry about with us in bottles, so that by simply opening a little valve in the bottle we can inhale some of the air now and then when we are in the other rooms. By adopting this plan, I hope when we reach Mars we shall all have become so acclimatised that we shall be able to breathe the Martian air without much inconvenience."

"Heh, Professor," said M'Allister, "what a mon you are for planning things out; I would never have thought of that!"

"John had quite as much to do with the planning out as I had," I replied; "and as you now understand what we propose to do, we will at once commence our training, but we shall not feel much difference in the air for the next day or two."

We accordingly put our plan into operation, each of us making up at least eight hours' time every day in the Martian air-chamber, with the result that we gradually became accustomed to the thinner air, and could breathe it without any feeling of inconvenience.

As the days went on I began to notice that John was becoming very irritable; and so was I, though to a lesser extent. The closer confinement to one room was evidently beginning to tell upon us, and day by day the effects were more apparent on both of us, especially in the case of John; but, strangely enough, whilst we were becoming more depressed and irritable, M'Allister's spirits seemed to be rising every day!

It has often been remarked that if two or three people are shut up together for a considerable time, with no other companionship or change, sooner or later they are bound to fall out with each other.

Up to the present we had all agreed splendidly, but now John's irritability seemed to increase hourly; and as regards myself, I often found it necessary to exercise very great self-control to avoid giving very sharp and snappish answers to John's peevish and querulous remarks.

But the inevitable explosion came at last, and, like all explosions, was very sudden and unexpected when it did happen.

All the morning of the 2nd of September John had been wandering in and out of the various rooms, and frowning as though very displeased about something. I gave him a hint or two that he ought to put in more time with me in the air-chamber, but he took no notice of my suggestions.

Presently, whilst I was in there alone, he came through, but, without speaking to me, went on into the store-room; and I heard him in there opening and shutting the lockers and cupboards, generally closing the doors with a loud bang, as persons do when in a very bad temper.

These bangs became more frequent and more violent, and at last succeeded each other with such rapidity that it seemed almost as though a vigorous cannonade were in progress.

I was wondering what could be the meaning of all this commotion, when suddenly the door opened, and John rushed into the room looking very cross indeed.

"I'm sorry, Professor," he cried, "though it's no use saying so; but we must go back to England again at once!"

"Good gracious, John!" I exclaimed, "what do you mean, and whatever has happened to upset you so and cause you to change your mind in this extraordinary way?"

"The deluge has happened," he replied, very crossly. "Professor, _I've left all my stock of tobacco behind_!"

"Never, John," I replied. "Why, you packed it up yourself; and I remember that when we overhauled the stores on our departure I saw the large tin of tobacco in your cupboard."

"I thought I packed it up," he answered, "but it's nowhere to be found now. As my tobacco supply had nearly run out I went to the cupboard this morning to get some more, and took down the big tin of twenty-six pounds labelled 'Tobacco.' I opened it, and what do you think it contained? You would never guess--well, it was tapioca!

"I've looked everywhere I can think of, without finding a trace of the weed."

Just then M'Allister came into the room, and, noticing John's vicious frown and my troubled look, asked what was wrong. We told him the news, but he only laughed, and, turning to John, exclaimed, "Heh, John, don't fash yourself about the tobacco, mon; we'll find you a subst.i.tute.

There's more kinds than one."

"Subst.i.tute, indeed!" said John snappishly, "no subst.i.tutes for me!"

"Well, John," I interposed, "you can have as much of my tobacco as you like; it's a good brand, you know, and I shall not mind a shorter allowance, for it does not mean much to me."

"No," he exclaimed sharply, "I can't take yours, Professor; it's your own special brand!"

"Well, John," said M'Allister, "you're as welcome to mine as if it were your own, and it's fine strong stuff too. And you can have some of my Navy plug as well," he added with a grin; "you'll find it rare good chewing."

"I simply cannot take the Professor's tobacco," said John; then, angrily turning upon poor M'Allister, he cried, "And as for your filthy stuff, it's a downright insult to offer it to me!"

"John! John!" I implored, "do be reasonable; it's not at all like you to talk in this rude way, and you must know we really cannot go back now!"

"Reasonable!" he sneered. "Do you call it reasonable, Professor, to ask a man who is a lover of his pipe to go all the way to Mars and stay there for months without any tobacco!"

"Well, you will not accept mine, although you know perfectly well that you are heartily welcome to it. It's not your own particular brand, it is true, but it is a real good one. However, most likely you will find some on Mars; there's plenty of vegetation on that planet, without a doubt."

"Vegetation be hanged!" he angrily exclaimed. "What am I to do in the meantime? As for tobacco growing upon Mars--why, sir, I'd bet my bottom dollar that, outside our own world, there's no place in the whole universe where anything equal to my superb mixture can be produced. It's no use talking, Professor; as I said before, we must go back."

"We cannot go back," I replied sternly, for by this time I was becoming very irritated at his obstinacy. "The idea of going back so many million miles merely to fetch tobacco! Remember, we have travelled at least 57,000,000 miles on the way to our destination!"

John strode up and down, becoming more and more excited every minute, and was soon quite raging; yet it seemed most singular that the more John raged the more M'Allister laughed. I looked from one to the other in amazement and the most utter perplexity at this extraordinary change in their behaviour. Then all at once I saw a gleam of light, so to speak, and the solution of the mystery became clear to me.

The air we had so long been breathing when in the air-chamber, and when we made use of our air-bottles, was very similar to what is popularly known as "laughing-gas"; and undoubtedly we were all more or less experiencing the c.u.mulative effects of the constant mild doses we had inhaled. Laughing-gas acts in a different manner upon persons of different temperaments: some will keep laughing, moderately or immoderately; others will become irritable, angry, or even pugnacious; whilst others again will weep copiously.

M'Allister was now talking rapidly and quietly to himself, laughing all the while, his eyes shining and twinkling merrily as though something intensely amusing were being enacted.

This seemed to react upon John, who apparently was irritated beyond control, and presently he roared out, "Kenneth M'Allister, stop that infernal grinning and chattering like a monkey! Stop it, I say! stop it directly!" But M'Allister took no notice and laughed louder than ever.

"Why, you confounded baboon," shouted John, "you're worse than any laughing hyena! Stop it, stop it at once, or I shall do you some mischief!" And he advanced towards M'Allister in such a menacing att.i.tude that I had to rush between them to keep them apart.

He was now raging up and down the room, looking as angry as a hungry lion which has just had a long expected dinner suddenly s.n.a.t.c.hed away from it; but the worse he became the louder M'Allister shrieked with laughter. The latter was now simply rolling about the room--for it could not be termed walking, it was so erratic--holding his sides and laughing, whilst the tears were chasing each other down his cheeks. He kept trying to speak, but had no sooner stuttered out the words, "Heh, mon! heh, mon!" than he was off again into another wild paroxysm of laughter, and was rapidly becoming exhausted.

Things were really becoming very serious indeed, and I saw that something must be done at once to put an end to this disturbance. So, going over to M'Allister, I took him gently by the shoulders and pushed him out of the room, saying quietly, "Go to your own room at once; but for goodness' sake don't touch the machinery until the air has had time to put you right again. Leave me to deal with John." He rolled off through the doorway, still laughing "fit to split" as people say.

Returning to John, I tried to calm him down; but it proved a long and difficult task, though at last I succeeded in persuading him to go with me into our living-room and sit down quietly.

After sitting there some time, puffing away at his pipe, the fresher air began to have its effect; and soon I judged that he was calm enough to talk the matter over and discuss the situation more reasonably.

Then I said: "John, my dear fellow, please listen to me. You know we have now travelled quite 57,000,000 miles on our journey, and that all our arrangements have been made with a view to reaching Mars not later than the 24th of September, because it will then be at the point where it is in opposition to the sun as seen from the earth. It is merely a sentimental reason so far as the opposition is concerned, but there are substantial reasons for not delaying our arrival.

"You say we must go back, but please consider all that such a course must involve. Though the earth has been following us up pretty closely on a slightly different course it is at the present about 13,000,000 miles away from us. You will see it out there on our left hand towards the rear of the _Areonal_; but we cannot go direct across to where it is now, for by the time we reached that point the earth would have gone ahead several million miles. Our only course is to head it off, and, taking the shortest line, that means a journey of over 12,000,000 miles.

Therefore, we cannot reach England until the 8th of September at the earliest, and as we shall require at least a week to lay in fresh stores, it will be the 15th before we can start again.

"Starting on the 15th September we should have to travel at least 54,000,000 miles before we could catch up Mars, and as that will take twenty-eight days, we could not arrive there before the 13th of October.

(See the chart.)

"Thus, we must sacrifice our chance of being upon Mars on the date of opposition, and also the opportunity of catching the first glimpse of our earth a few days later. If we continue our journey now and reach Mars on the 24th of September the earth will then be only 37,000,000 miles away; but by the 13th October it will be over 40,000,000 miles distant. There is the further objection that to get back again in reasonable time we must leave Mars by the 1st of December, and the loss of three weeks' time will deprive us of many opportunities of learning what there is to be found on the planet.

"Now, John, like a good fellow, just think over the matter quietly and reasonably; you will then realise that it is quite impossible to interrupt our journey and return to England as you suggest."

"I have thought it all out again and again," he replied, "and can only repeat, Professor, that it is quite impossible for me to go on minus my tobacco!"

"Was there ever such an obstinate and unreasonable man!" I thought to myself. "What can I do to put an end to this absurd difficulty?"

[Ill.u.s.tration: _DIAGRAM showing the relative positions of the Earth and Mars at the various Oppositions of Mars, from 1892 to 1924._

_Past Oppositions are shewn by the firm lines with the dates outside the Orbit of Mars. Coming Oppositions are indicated by the dotted lines with the dates inside the Orbit._

_The distance between any two consecutive Oppositions represents the distance in excess of one complete revolution in its...o...b..t pa.s.sed over by the planet since the last preceding Opposition. These distances are greater on the left hand side because of the planet then being nearer the Sun and consequently travelling more rapidly._

_Drawn by M. Wicks._