A few weeks later I received a letter from Dr. Anderwelt asking me to call at his rooms on the West Side that afternoon, as soon as the market had closed. He desired to exhibit and explain the drawings of the new projectile and talk over the preparations for the trip. I had been so engrossed with every sort of worry that I had thought but little of the doctor and his grand schemes of late. But now I was anxious to know what progress he was making. Sometimes I felt that I had been foolish to put any money into the thing; but the doctor's idea of reversing gravity was so simple and so elemental, that I marvelled it had never occurred to scientists before.

After the market I hunted up the street and number the doctor had given me, and found a little, dingy boarding-house, lost among machine shops and implement factories, near the west side of the river. In a third-floor back room, with one small window looking out on dark, sooty buildings and belching chimneys, Dr. Anderwelt was thinking out all the incidental problems, and preparing for all the emergencies that might arise on a trip of some forty million miles, through unknown space, to a strange planet whose composition was unguessed.

The walls of the room were soiled and bare, except for blue-prints of drawings from which the projectile was being built in neighbouring foundries. There were but two plain, hard chairs in the room. The doctor sat on one with a pillow doubled up under him for a cushion. He was bending over a draughting board, which was propped up on the bed during the day and went under it at night.

Three flights of steep stairs had taken my breath, and I dropped into the other hard chair and exclaimed,—

"I say, Doctor, why didn't you take an office in the twelfth heaven of a modern office building over in town, where they have elevators? I have really forgotten how to climb stairs. Didn't I furnish you money enough to do this thing right?"

"Don't you think this is a good place?" he inquired in some surprise. "The rent is cheap, and it is convenient to the work. But speaking of elevators, we are going to revolutionize all that. No more hoisting or hydraulic lifts after we apply our ideas to the lifting of these elevator cages!"

"I am afraid this idea of negative gravity is apt to revolutionize everything, and generally upset the entire universe," I replied. "I have been wondering what would happen if you were to apply a negative current to this Earth of ours and send it whirling out of its orbit, an ostracised Pariah, repelled by all the celestial bodies!"

"Not the slightest danger of any such calamity," he answered. "The reversal of polarity can only be accomplished with comparatively small and insignificant masses. It would be impossible to impart a negative condition even to the smallest satellite. Our projectile will weigh but a few thousand pounds, compared to the millions of tons of the smallest celestial bodies. The Creator has looked out for the stability of the universe, never fear for that! And He has also given us a few hints of negative currents and repellant gravities in the form of meteorites and falling stars, which cannot be so well explained by any other theory. But what I want to talk to you about is the vital importance of providing against every possible emergency before starting on this trip through space. A trifling oversight in the preparations may mean death in the end, and things we put no value on here we might be willing to give a fortune for on Mars!"

"Well, let's hear how this thing is built," I said, rising and facing the larger blue-print. "So that's the shape of it, is it? Looks like a cigar!"

"Yes, the design resembles that of a torpedo considerably," replied the doctor, and referring to the sectional blue-print he began explaining the construction.

"This outer covering is a crust of graphite or black lead, inside which is a two-inch layer of asbestos. Both of these resist enormous heats, and they will prevent our burning by friction with atmospheres, and protect us against extremes of cold. Also, when we are ready, they will enable us to visit planets about whose cooled condition we are not certain. We might touch safely for a short time on a molten planet with this covering.

"Next comes the general outer framework of steel, just within which, and completely surrounding the living compartments, are the chambers for the storage of condensed air for use on the trip. These chambers are lined inside with another layer of asbestos. Now, air being a comparatively poor conductor of heat, and asbestos one of the best non-conductors we know of, this insures a stable temperature of the living compartments, regardless of the condition without, whether of extreme heat or extreme cold. Afterward comes the inner framework of steel, and lastly a wainscotting of hard wood to give the compartments a finish."

"How large are these living rooms?" I inquired.

"The rear one is four feet high and eight feet long. The forward one, designed for my own use, is longer, and must contain a good-size telescope and all my scientific instruments. The apparatus with which I produce the currents is built into the left wall, and it acts on the steel work of the projectile only. The rear compartment has a sideboard for preparing meals, which will have to be wholly of bread, biscuits, and various tinned vegetables and meats. We shall not attempt any cooking."

"But are there no windows for looking out?" I queried.

"Certainly, there are two of them, made of thick mica. One is directly in the front end, through which my telescope will look. The other is in the port-hole in the rear end. Each window is provided with an outer shutter of asbestos, which can be closed in case of great heat or cold. You will notice the two compartments can be separated by an air-tight plunger, fitting into the aperture between them. It will be necessary for both of us to occupy the same compartment while the air is being changed in the other. The foul air will be forced outside by a powerful pump until a partial vacuum is created. Then a certain measure of condensed air is emptied in, and expands until the barometer in that compartment indicates a proper pressure."

"The air will be made to order while you wait, then?" I put in.

"That is exactly what will be done in a more literal manner than you may suppose!" exclaimed the doctor. "This air problem is a most interesting one, for we must educate ourselves on the trip to use the sort of atmosphere we expect to find when we land. For instance, going to Mars we must use an atmosphere more and more rarefied each day, until gradually we become used to the thin air we expect to find there. Of course, there is an especially designed barometer and thermometer, capable of being read in the rear compartment, but exposed outside near the rudder. The barometer will give us the pressure of the earthly atmosphere as it becomes more and more rare with our ascent. It will show us what pressure there is of the ether, which may vary considerably, depending on our nearness to heavenly bodies. It will also immediately indicate to us when we are entering any new atmosphere. When we have arrived at Mars, we shall observe the exact pressure of the Martian air, and then manufacture one of the same pressure inside, and try breathing it before we venture out. The thermometer will give us the temperature of the ether, will indicate the loss of heat as we leave the sun, and will show us the Martian temperature before we venture into it."

"But you have said the condensed air will be used to resist the outer heat. This will certainly make it so hot it will be unfit to breathe," I interposed.

"Ah, but you forget that the quick expansion of a gaslike air produces cold. We shall regulate our temperature in that way. If it is becoming too warm inside, the new measure of condensed air will be quickly introduced into the partial vacuum, and its sudden expansion will produce great cold, and freeze ice for us if we wish it. On the other hand, if the compartments are already cold, we shall allow the condensed air to enter very gradually, and its slow expansion will produce but little cold. The question of heating the projectile is the most difficult one I have found. We cannot have any fires, for there is no way for the smoke to escape, and we cannot carry oxygen enough to keep them burning. I have decided that we must depend on the heat arising from outer friction and from absorption of the Sun's rays by our black surface. When we are in ether where friction is very little, the velocity will be all the greater, and I believe we shall always be warm enough. You must remember, we shall not have the slightest suspicion of a draught, and we must necessarily take along the warmest clothing for use on Mars. Even then we probably cannot safely visit any but his equatorial districts."

"This is the rudder, I suppose; but haven't you put it in wrong end first?" I asked. "It is just the opposite of a fish's tail. You have the widened end near the projectile and the narrow end extending."

"Yes, and with good reason. You will note that the rudder slides into the rear end of the projectile so that none of it extends out. This is a variable steering apparatus, adapted to every sort of atmosphere. Naturally, a rudder that would steer in the water, might not steer the same craft in the air. There is probably a vaster difference between air and ether than between water and air. It is necessary, therefore, to have a small rudder with but little extending surface in thick atmosphere; but when it becomes thinner the rudder must be pushed out, so that a greater surface will offer resistance. When we start, the smallest portion of this rudder moved but the sixteenth of an inch, up, down, or to either side, will quickly change our course correspondingly. When we have reached the ether, the full surface of the rudder pushed out and exposed broadside may not have much effect in changing our course. This is one of the things that we cannot possibly know till we try. However, if ether is anything at all but a name, if it is the thinnest, lightest conceivable gas, and we are rushing through it at a speed of a thousand miles a minute, our rudder certainly should have some effect."

"But suppose you cannot steer at all in the ether, what then?" I interposed, hunting all the trouble possible.

"Even that will not be so very dreadful, provided we have taken a true course for Mars while coming through the Earth's atmosphere. There is no other planet or star nearer to us than Mars when in opposition. Therefore there will be nothing to attract us out of our correct course; and if we can manage to come anywhere near the true course, the gravitational attraction of Mars will draw us to him in a straight line. The Moon might give us some trouble, and we shall be obliged, either to avoid her entirely by starting so as to cross her orbit when she is on the opposite side of the Earth, or else go directly to the Moon, land there, and make a new start. But if the ether which surrounds the Moon (for she has no atmosphere so far as we know) has no resisting power whatever, we might have rather a difficult time there. The only thing we could do would be to land on the side toward the Earth, then disembark and carry the projectile on our shoulders around the Moon to the opposite side, making a new start from there!"

"What on earth do you mean?" I exclaimed, interrupting. "Land on a satellite which has no atmosphere, and carry this projectile, weighing over a ton, half-way around the globe?"

"But the point is, it isn't on the Earth, but on the Moon! Think it over a little, and see how easily we could do it now. In the first place, we shall always carry divers' suits and helmets, to use in going ashore on planets having no atmosphere. Air will be furnished through tubes from inside the compartments. In the second place, the projectile in its natural state will hardly weigh two hundred pounds on the Moon, since the mass of that satellite is so much less than the Earth's, and weight therefore proportionately less. But you must remember I can make the projectile weigh nothing at all, so one of us could run ahead and tow it, as a child would play with its toy balloon."

"I perceive you have already made this trip several times, and are quite familiar with everything. But in case the Moon's surface is not suitable for foot passengers, what then? I understand it to be rough, jagged, mountainous, and even crossed by immense, yawning, unbridged fissures."

"That is most likely true, and for that reason we must carry a jointed punt-pole, and take turns standing on the back, landing and punting along through space just above the surface. Do you remember how far you can send a slightly shrunk toy balloon with one light blow? And how it finally stops with the resistance of the air? Without any resisting atmosphere, how far and how easily could it be sent along?"

"I can quite imagine you, astride the rudder of this thing, with a punt-pole as long as a ship's mast and as light as a broom-straw, bumping and skipping along in the utter darkness on the other side of the Moon; scaling mountains, bridging yawning chasms, and skimming over sombre sea-beds!" I laughed, for it aroused my active sense of the ridiculous.

"And the Moon may be well worth the exploration," exclaimed the always serious doctor. "Who knows what treasure of gold and silver, or other metals, rare and precious here, may not be found there? Why was the Moon ever created without an atmosphere, and therefore probably without the possibility of ever being inhabited? Is it put there only to illume our nights? Remember, we do the same service for her fourteen times as well; and if she has inhabitants they may think the Earth exists only for that purpose. Is it not more reasonable to suppose that some vast treasures are there, which the Earth will some day be in pressing need of? That it is a great warehouse of earthly necessities, which will be discovered just as they are being exhausted here? And who knows but we may be the discoverers ourselves? If the satellite is uninhabited, it will belong to the first explorers. Its treasures may be ours! We shall at least have a monopoly on the only known method of getting there and bringing them away."

"Ah! now you tempt me to go with you," I said, in a mild excitement. "Now I see myself, erect on the rudder, a new Count of Monte Cristo, waving the long punt-pole majestically, and exclaiming, 'The Moon is mine!'"