“Deimos is exceedingly valuable also as a sort of stepping stone from which to get onto Phobos. Once on Deimos and it is as easy getting onto Phobos as to step from one car to another in a running train. Phobos is 5,807 miles from the center of Mars. When the three are in line it is 8,740 miles from Deimos. Deimos travels 3,016? miles an hour, Phobos 4,777. A body thrown off from Deimos towards Mars will retain the velocity of Deimos and will acquire in falling that 8,740 miles an additional velocity enough to bring its speed up to that of Phobos. So our Lunarians by close calculation and timely departure from Deimos have had little or no trouble in lighting on Phobos without a perceptible jar and have conveyed by that route all the machinery and apparatus they needed in making their improvements there.” “Was Phobos worth improving then?”
“No, its motive power was simply harnessed so as to be utilized on Mars. They did it in this way.
“A large number of powerful steel magnets were prepared on Mars together with the materials for a large basket or crate stout enough to hold them,[269] also four cables made of wire, each two inches in diameter. These materials done up in proper shape were taken up the cable by repulsion to Deimos then again by repulsion cast off with a company of Lunarians in one of their cars to sail down to Phobos.”
“I should think that being encumbered with such a lot of stuff would have added greatly to the risk of the trip,” said I.
“Not at all, the more metal the better, since it can be made light or heavy at will and so kept under control while other materials could not be made light. It is always desirable to have more than half the weight of our outfit in iron or steel on that account. Well, they landed this material on Phobos and there put it together. The different parts were insulated from each other to provide for the use of repulsion or gravitation as the case might require.
“They staked off an exact square five and a half miles on each side, which was about as large a one as they could get on Phobos and at each corner they firmly anchored one end of one of the cables. At the center of the square Mars appeared directly overhead. At this point the crate was put together upside down and its load of magnets arranged inside of it also upside down. The cables 3,760 miles long were coiled in a pile each to itself and the end fastened to the corners of the crate. On Mars this outfit weighed many tons, but on Phobos it was so light that one man could lift it. Wires connected with a battery passed through the cables to regulate the weight of the[270] concern. A small amount of repulsion raised it and carried it to the limit of the attraction of Phobos. The momentum taking it a little further, and within the dominance of that of Mars when light attraction was turned on and the crate rose or rather fell slowly toward Mars. When the cables were stretched out and the crate hung by them, it was within a few feet of the ground in some places, at others as much as one or two hundred. Its motion was from west to east at the incredible speed of 1,160 miles an hour. Its actual rate of travel is 1,681 miles per hour, but the revolution of Mars on its axis is at the rate 521 miles in the same direction, so the difference constitutes the apparent motion of the crate of Magnets. In order to get electric power from these it was only necessary to set up insulated slabs of soft iron along the route of the magnets in such position that they would pass close to them as they swept by. This was done at different places along the route, and covered altogether, distances aggregating more than three thousand miles. Of the remaining distance around the planet a part was over the sea and some over low land, where the scaffolding would be too high to pay. The electricity generated in these stationary armatures was run off to storage batteries wherever required in the equatorial regions of the planet. So, with the cable to Deimos and the big dynamo of Phobos. Mars is supplied with unlimited power at nominal cost.”
“But doesn’t the plant require renewal? I should think it would rust out after awhile.”
“Yes the cable has been renewed twice. The[271] last one put up is 12 inches in diameter. It is easy now to put one up, with the one already up to steady and steer it. It only has to fall up as you might say, under the influence of repulsion. The occasion of putting up the last cable, however, was not rust, but a singular accident. During the winter there are generally only two or three men left at the pole to keep the shaft oiled and see that everything is all right. One winter the men left in charge undertook to move some heavy timbers and steel beams that had been left on the top of the mountain, and managed to get them into such a position that they were caught by the cable which slowly carried them around until they partly fell into a crevice and became immovable. The cable bent itself around the obstruction, and in doing so was thrown so far down over the edge of the mountain which as I told you had been turned off to resemble a capstan, that it began to be wound around it as if it were a great spool. The men telegraphed to the general manager who came up with a crowd of engineers and workmen, but they could not do a thing except to keep the cable raised by repulsion as much as possible to keep it from catching some obstruction on the ground. The cable made the complete circuit of the railway track in a trifle over 5? days. The mountain stem had been whittled down to about a mile in diameter so that each revolution wound up a little over three miles of cable, which was at the rate of a little over half a mile a day.
“The cable was so injured where it had been[272] wound up that they were afraid it would break if they loosened it, and so they concluded to make a new one. There did not seem to be any great hurry about it, and so it dragged along for four years without much being done. By that time almost 700 miles of cable had been wound up and Deimos had been drawn up that much nearer to Mars. Some thought this a good thing and proposed to let him wind himself down within a hundred miles or so of Mars, so that he would be of some account as a moon, for he gave very little light where he was. Others wanted him pulled down to the ground so they could cut him up and get the gold, silver, iron and other valuables he might contain; enough they said to make all the Martians rich. But the more prudent pointed out that if he was pulled down too far he would interfere with Lucy Phobos and spoil her work. It had been observed that the cable had been getting slower and slower and was now moving only a little more than half as fast as it did at first, and the industries depending on it were getting short of power. The mathematicians figured that Deimos would never wind himself up any closer than 12,700 miles or 1,847 miles from where he was in the first place, for the reason that drawing him in towards Mars increased his speed so that when he was wound up to 12,700 miles he would revolve around the planet in 24 hours and 40 minutes, the same time it takes Mars to roll over. Consequently Deimos would appear to stand over the same spot all the time, the cable would cease to move and the winding up process would[273] stop, and of course all the machinery connected with it would stop too. After a full discussion of the matter, it was concluded to let Deimos get back to his original orbit, so that the manufacturing that had been started and was operated by the power furnished by the cable might not suffer any further loss.
The New Cable.
 
“The new cable was run up alongside of the old and the upper end fastened to Deimos while the eye in the lower end was placed over the shaft. The cable was then deprived of weight and the 700 miles of slack floated about in space like a big cobweb. It was now supposed that if the old cable was cut Deimos would rapidly move out to his old position. But he did nothing of the kind. He seemed to be satisfied with his new route, and for several months he persistently kept on without getting any further away, his slack cable sagging out behind. They now undertook to compel him, and they succeeded in this way. They gave the cable full weight repulsion. This caused it to straighten out upward, and the slack went on up 350 miles above Deimos curving back to him. The whole thing looked like a fish pole and line with Deimos dangling at the end of it. It had the desired effect, however, for its strain upward exerted considerable power on Deimos disturbing the equilibrium that had been established between the centripetal and centrifugal forces that controlled his motion. It took about two years, however, to get him back to his old route. He was[274] tipped over twice in the process, on account of the cable having been fastened on the underside; first while the loop of the cable was above it, and second when it got out to the end of the cable it was canted back again.”
“It was a funny experience, the little moon had,” I observed. “I suppose it got down to its former gait so as to allow of the old retrograde speed of cable at the Mars end?”
“Yes of course, the speed of Deimos decreased with its distance from Mars. It has occurred to them since, that they ought to have had a still longer cable, so as to have got him still further off with a still slower movement. They would have got more power by it.
“The last time I was on Mars a remarkable circumstance took place that I shall never forget. I was one of a party that accompanied the King on a visit to the pole to inspect the plant and view the landscape. From this lofty elevation the view is charming, and there is also a strange fascination in watching the solemn revolution of the great cable moving with the deliberation and precise regularity of the hour hand of some enormous time piece. There is a little cabin built over the shaft at the pole which revolves with the cable. The man whose business it is to oil the shaft constantly stays in that cabin, and even sleeps there. While we were admiring the view we suddenly heard a scream from the man in the cabin. The eye of the cable is oval and is not filled by the shaft at its inside end. Upon rushing into the cabin we found the unfortunate man had been asleep and[275] allowed one of his feet to drop into this space and it had been slowly drawn in between the cable and the shaft until it was so fastened that he could not pull it out with the most frantic exertions, and every minute took it further crushing as it went. At last the man called for an ax, and it was handed to him, when without a moment’s hesitation, with two or three strokes he severed his leg just above the knee. I was terribly shocked, but the poor man made light of it, and declared he would have another leg in its place as good as that one in five months. Less than two weeks afterwards I saw him and his leg had already started to grow out and in five months he was walking on it the same as the others.”
“That was remarkable,” said I, “but it is said the star fishes on earth—what! are you going?”
The professor during his talk............