it gives Sag some idea of what it must be. In sig- nalling Queensland or British Columbia I have often noticed there is no interval at all detectable. "How is it then," I asked, "that if you are not a' human being, you speak to me with a human voice?" "A very reasonable question," said the voice, "showing that you realize that the sounds of hu- man speech could only be made by human, or in some measure human-like organs. But the explana- tion is very simple. When first radio telephony was invented by you, that is, when first we heard your voice on our receivers, we immediately learned your languages. (That you should have more than one shows how crude is still your sociak^-but of that later.) Our next care was to make a mechanism that could give out the sounds alluded to. This I employ as you might play on an organ, and it is sounds so produced that you hear." The Wonderful Intelligence of the Venus.People AS I listened to these last words of the voice I felt a lightening of the load of dread, the suspicion of my own insanity, that weighed on me. Surely, mad or sane, no sueh ideas could spring up spontaneously in my head. Some one, somewhere was communicating with me. "Until you used radio telephony, we were ignor- iant of the sounds you made in communicating with each other; and it seems to be practically sounds alone that you employ — a curious limitation!" "But," I said, "you could see us before that? .You knew that this world was inhabited?" "We have known it for a hundred thousand years, and more, and during all that time have been close and interested observers of the happenings on your ._ globe, placed as you are peculiarly well for our ofeeKwiipn. While we were still not, on the whole, more advanced mentally than you are now, we had already constructed an instrument which enabled us to do this. The fact that you have not yet done so is because you are mentally constituted in a totally different manner, which inclines you to devote your study and efforts in other directions. That is to say, primarily so. The observation of nature, and the universe in which we live, would appear to you of infinitely less importance than matters which, to us, appear futile and trivial." "lam sorry that I have not had the time to study these things," I said, "but I thought Mars was the nearest world to us, not Venus; and I have seen some talk about its being perhaps inhabited. I should take an interest in science, but I have had no time, with my living to get." "N us as information of practical benefit to ourselves. On hearing that the present conversation was about to end, I said, "Will you, or can you, give me soma proof, that others will accept, that this conversation has actually taken place, and is not merely my own imagination?" "What kind of proof do you suggest?" "Something that could not he known to me in" any other way, as, for instance, a description of the thing you said you could see us with so long ago, when no cleverer than we are. Nobody could believe that I had invented sueh a thing as that must be." "Very well ! As you may not be able to follow all the description, which I must render short, write with care the words you hear, so that others may be able to understand it, even where you may not ba able to do so. "Given perfect workmanship, the power of a tele- scope depends on the area of its objective lens. This is not on aeeount of any superiority of defini- tion, but on its greater light-gathering power. The image it produces is capable of greater magnifica- tion because better illuminated. But beyond certain moderate dimensions the practical difficulties in the making of optically perfect objectives increases out of proportion to the extra area. For this reason our savants turned their endeavors to the discovery of some way of making a number of objectives, ar- ranged in series, yield one perfect image of the object. Double Refraction aiid Polarization "'TVHERE are certain crystals, which probably I you have personally never heard of, which A are doubly refracting. When a single ray of light enters one of these crystals in a certain direction it divides into two, which proceed in di- verging paths and emerge as two rays. If the ray or beam of light entering the crystal carries an im- age of some object, the sides of the crystal can easily be so cut that' both the emerging beams carry per- fectly the same image. Conversely, if two rays enter the crystal in the paths by which the first mentioned left it, they will unite and emerge as one ray. "The rest is obvious. A batteEjroj; objectives and as many intervening crystals is arranged. Into each intervening crystal enter two beams in the requisite paths mentioned, the one of which comes from tha object direct through one of the objectives, the other is the emerging beam from the crystal next before it in series, and which is the united beams from an objective and the crystal still next before. By this means the beam emerging from the crystal last in series is composed of the united beams of all doubt," said the voice, "but your savants "the objectives, and,' if the manufacture and optical will be under no misapprehension as to the" arangement is perfect, will carry a perfect .i^aage of the object, with light in proportion to the united area, of all the objectives. The arrange- ment of the minor lenses, and the method of deal- ing with the polarization, will be so obvious to your opticians that it can be here omitted." "What," I said, "is polarization?" "There is no time now," said the voice, "for fur- ther description, and the fact that you do not know, renders my description the more valuable to yOu for the purpose for which you asked it. Your-~ people will know all about it. We must now cease Mars Is Also Inhabited relative distances of Venu3 and Mars. You have seen more respecting Mars because it is better placed for your observation. I can inform you that it is inhabited. Of all the things we shall speak of, this is the most vital. to you. But we will not enter on it until to-morrow, as the time for our present conversation is now nearly ended." This, of course, seemed very surprising to me, and I cannot now see at all what it could mean. It does not seem to me that any news about the inhabi- tants of Mars could be of much importance to