THERE are those who accept of the fancies of astronomers as facts of astronomy, and who believe that some great telescope or lens will be made which will reveal all about the moon, tell us whether Mars is inhabited, etc. To such and all, the following from Prof. E. E. Barnard, one of the kings in astronomy, on the possibilities and probabilities of the great Yerkes glass, may be of interest. The extracts below are taken from an article in the San Francisco Examiner of June 7:— Of refracting telescopes—the most powerful form—the Yerkes is the greatest ever made in point of both size and power. It stands theoretically one-fourth more powerful than the great Lick telescope—the pride, and justly so, of California. The first, and one of the most important statements, is that too much must not be expected from the new telescope. It is only those who have worked with great telescopes who can fully appreciate this remark. If we did not have to deal with the disturbances ever present in our atmosphere, one might give the imagination a great deal of freedom in predicting what a great telescope is likely to do. Every tremor in the atmosphere is multiplied in its disturbing effects by the power of the telescope, and this tends to destroy the image of any object under observation. In reference to Mars, it is expected that its surface will be seen better than in any other telescope, but all the sensational ideas about what may be revealed on this planet had better be laid aside at once. The great telescope will probably disprove many of the absurd ideas now propagated about Mars. So far as seeing the probable inhabitant of Mars, or any of his works, is concerned, nothing more absurd was ever conceived. We shall see the planet better than it has been seen, but how little that means for the possible inhabitant of that planet can only be fully appreciated by those who use telescopes, and not by those who write about them. The great telescope will enable us to more accurately determine the distances of the fixed stars, but it is not expected that it will show us the true disk of a fixed star, from which its actual size could be determined. This is possibly beyond the reach of any telescope that will ever be made. The moon will be better seen, and some information of value may be obtained concerning it, tho very much is not expected in this direction. A greater telescope will only reveal more little hills and valleys on the desolate surface of the moon, but the step that will tell us what it is composed of, and whether it ever bore life upon its surface, is one so enormous that it can not be expected of any telescope yet to be constructed. Much has been said about the closeness to which the forty-inch lens will bring the moon to the earth. Theoretically it could be brought to within a comparatively few miles, but under such conditions that nothing could be made out of it. There is a limit at which the best results can be obtained. If this limit is forced, the image is blurred, and the surface is not as well seen as with a lower power. I would say that under the best conditions, with the great telescope, the moon would look as if seen with the naked eye at a distance of from 150 to 200 miles. Of course it has been stated that the moon would be brought much nearer than this, but it would not be well seen under such conditions, and no advantage would be gained. Indeed, it would be a decided loss on account of distinctness. In conclusion, I would say that the magnificent gift of Mr. Yerkes to the University of Chicago will very greatly advance the science of astronomy along many lines, and will stand a lasting monument to the munificence of its founder. So far, however, as news of a sensational nature is concerned, nothing whatever can be expected from it, as the telescope is in the hands of men who do not take kindly to that form of 'science.'