/> to make a diminution in the apparent sizes of the sun and Venus; and

there was a gradual increase in the size of the planets, Mars and

Saturn, towards which we were moving. As regards the fixed stars,

however, there was no change in our surroundings, as they are such an

immense distance away-the nearest being, at least, twenty billions of

miles from the earth, that a few million miles more or less make no

difference in their apparent size, or in their positions in regard to

each other in the constellations as we know them in our maps.



As we were now fairly on our way, and moving rapidly in the direction we

wished to travel, I thought it quite time to put into operation a scheme

which John and I had previously decided upon, so I told M'Allister that

he must be prepared to take a little change of air.



"Why, Professor," he exclaimed, "that sounds almost like a proposal for

going to the seaside!"



"We certainly are not going there," I replied, "for we are rapidly

moving away from all seaside resorts, and you are not likely to visit

any of those places for a very long time to come."



"Well, mon, where are we going to get our change of air then?" he

inquired; "you know there's no air at all outside of this vessel."



"Quite true," I answered; "so we must get our change of air inside the

vessel."



"Yes," interposed John, "and, Kenneth M'Allister, you will have to make

up your mind to have rather short commons of it; the same as we shall!"



"Whatever do you mean?" he inquired, now appearing really scared-for a

dreadful thought had crossed his mind. "Mon, you surely do not mean that

our machinery is giving out!"



"Oh no! not at all, M'Allister," I replied; "but perhaps I had better

give you a full explanation of the matter:-



"You know we are bound for the planet Mars, where the air is very much

thinner than that which we have been accustomed to breathe, and very

probably it is composed of somewhat different constituents. In these

circumstances you will understand that, if we landed upon Mars without

having taken proper precautions, such thin air might make us very ill,

even if it did not kill us.



"That little compartment next the store-room was arranged and fitted up

for the special purpose of supplying a thin air in which we could

prepare ourselves for the atmosphere of the red planet. So we are really

going into training. The machines in that room will generate an

attenuated atmosphere somewhat similar to our own, and this will be

automatically mixed in a cylinder with a little oxygen and nitrous oxide

gas, so as to make it as near as possible like what we expect to find

upon Mars. When we commence it will be only slightly different from our

own air; then gradually we shall reduce its density and change its

quality until it is as thin as we shall require. Each of us must spend

about eight hours a day in that little compartment, though it will not

be necessary to take the eight hours continuously, for we may spend a

few intervals in the other rooms.



"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 substitute.

There's more kinds than one."



"Substitute, indeed!" said John snappishly, "no substitutes 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 cumulative 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

attitude 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 snatched 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?"




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 orbit passed 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.



Plate VI]



Resuming the conversation, and keeping as calm as I could in the

circumstances, I placed the matter before him in all its aspects, and

after we had been talking together for a long time, he seemed to be able

to take a more reasonable view of the position. In order that something

might be done to keep his mind from dwelling upon his proposal to return

to England, I suggested that we should go to the store-room and

thoroughly overhaul it.



He agreed to this, accompanying me to the store-room and pointing out

the different places he had searched. The tins were in several sizes,

but all were made square in order that not an inch of the available

space might be wasted. We looked into a large number of tins which had

not previously been examined, but without finding what we wanted.



At last a thought occurred to me, and I said: "You tell me, John, that

you are quite certain you put up the tobacco and labelled the tin

yourself, yet the tin so labelled was found to contain tapioca! Do you

remember where the tapioca was stowed away?"



He pondered awhile, with his chin resting upon his fingers, then

suddenly replied, "Yes, I think I know where it is," and, taking me over

to another cupboard at the far end of the room, we made a further search

and at last found the tapioca tin, opened it, and lo, there was the

missing tobacco!



"Well, I'm blest!" said John, very slowly drawing out the words; then

all his ill-humour suddenly vanished, and he burst into a most hearty

laugh, in which I joined. Our laughter, indeed, was so mutually

contagious, and so often renewed, that we had to sit down to finish it

and recover ourselves.



Then John remarked, "Now, Professor, I think I can explain it all. You

see I prepared and labelled those confounded tins before loading them

up; so I suppose that when stowing away the parcels of tobacco I just

glanced at the label on the tin and saw the letter T followed by the

right number of other letters, and, taking it for granted that it was

the tobacco tin, placed the tobacco in it. The only other tin left to

pack was the one I supposed to be labelled 'Tapioca,' and no doubt,

without troubling to look at the label at all, I put the tapioca into

it; but, of course, it must really have been the tin labelled

'Tobacco.'"



Thus the matter was satisfactorily cleared up. John, having found his

beloved weed and recovered from the effects of our patent Martian air,

was now quite himself again, seeming very contrite, and apologising

repeatedly for his rude conduct.



"That's enough, John," I said, as I laid my hand on his arm; "it is

quite clear that what you did was mainly the result of the peculiar air

you had been breathing, so I cannot blame you much. If I had not taken

so many intervals in the purer air, I might perhaps have been equally

affected; as it was, my temper was none of the sweetest."



M'Allister had also quite recovered by this time, and bore no ill-will

towards John; indeed, I doubt whether he had any very clear recollection

of what had occurred.



So that ended the matter; and this little explosion having cleared the

air, we all settled down to our old amicable relationship. We, however,

took the precaution of reducing the amount of nitrous-oxide gas in our

mixture of air, with a view to preventing any similar untoward results

in future.