The entire cost of the instrument is said to be over 2,000,000 francs. With the wonderful strides of improvement in all fields of invention, it is not unreasonable to suppose that the revelations in astronomy may keep pace with those of mundane interest, and that great discoveries may be made in the near future. The average individual does not bother himself much about the calculation of eclipses, or the laws which govern the movements of an erratic comet. He is, however, intensely personal and neighborly, and what he wants to know is, Is Mars inhabited? and if so, are its denizens men, and may we communicate with them? The wonderful regularity of the so-called canals, of apparently intelligent design, already discovered on the surface of Mars, has stimulated this neighborly curiosity into an expectant interest, and who knows what marvelous introductions the modern telescope may bring about? [Illustration: FIG. 196.--PROF. ABBE’S STEREO-BINOCULAR.] Many minor improvements have been made in recent years in the form of the telescope known as field and opera glasses. Probably the most important of these is the Stereo-Binocular, invented by Prof. Abbe, of Germany, and patented by him in that country in 1893, and also in the United States, June 22, 1897, No. 584,976. This gives a much increased field, and also an increased stereoscopic effect, or conception of relative distance, by having the object glasses wider apart than the eyes of the observer. The field is also flatter, the instrument rendered very much smaller and more compact, and no change of focus is required for changing from near-by to remote objects. The rays of light, see Fig. 196, enter the object glasses, strike a double reflecting prism, and are first thrown away from the observer, and then striking another double reflecting prism, arranged after Porro’s method, are returned to the observer in line with the eye-piece. [Illustration: FIG. 197.--MODERN MICROSCOPE.]