744 KANSAS CITY REVIEW OF SCIENCE. 
with a microscope, and magnified; thus came the telescope revealing unheard of 
suns and galaxies. The first telescopes colored everything looked at, but by a 
hundred years of mathematical research, the proper curvature of objectives formed 
of two glasses was discovered, so that now we have perfect instruments. Great 
results followed; one can now peer into the profound solitudes of space, bringing 
to view millions of stars, requiring light 5,000 years to traverse their awful dis- 
tance, and behold suns wheeling around suns, and thousands of nebule, or ag- 
. glomerations of stars so distant as to send us confused light, appearing like faint 
gauze-like structures in measureless voids. The modern telescope has astonishing 
power, thus: When Mr. Clark finished the great 26-inch Equatorial, now at 
Washington, he tested its seeing properties. A photographic calligraph whose 
letters were so fine as to require a microscope to see them, was placed at a dis- 
tance of three hundred feet. Mr. Clark turned the great eye upon the invisible 
thing and read the writing with ease, But a greater feat than this was accomplish- 
ed by the same instrument—the discovery of the two littke moons of Mars, by 
Prof. Asaph Hall, in 1877. They are so small as to be incapable of measurement 
by ordinary means, but with an ingenious photometer devised by Prof. Pickering 
of Harvard College, he determined the outer satellite to be six, and the inner seven 
miles in diameter. The discovery of these minute bodies seems past belief, and 
will appear more so, when it is told that the task is equal to that of viewing a 
luminous ball two inches in diameter suspended above Boston, by the telescope 
situated in the city of New York. [Newcomb and Holden’s Astronomy, p. 338. 
Phobos, the nearest moon, is only 4,000 miles from the surface of Mars, and 
is obliged to move with such great velocity to prevent falling, that it actually 
makes a circuit about its primary in only 7 hours 38 minutes. But Mars turns on 
its axis in 24 hours 37 minutes, so the moon goes round three times, while Mars 
does once, hence it rises in the west and sets in the east, making one day of Mars 
equal three of its months. This moon changes every two hours, passing all phases 
in a single Martial night; is anomalous in the solar system, and tends to subvert 
that theory of cosmic evolution wherein a rotating gaseous sun cast off concen- 
tric rings, afterward becoming planets. Astronomers were not satisfied with the 
telescope; true, they beheld the phenomena of the solar system; planets rotating 
on axes, and satellites revolving about them. They saw sunspots, facule and 
solar upheaval; watched eclipses, transits, and the alternations of summer and 
winter on Mars, and detected the laws of gravity and motion in the system to 
which the earth belongs. They then devised the Micrometer. This is a complex 
mechanism placed in the focus of a telescope, and by its use any object, provid- 
ing it shows a disc, no matter what its distance, can be measured. It consists 
of spider webs set within a graduated metallic circle, the webs movable by 
screws, and the whole instrument capable of rotating about the collimation axis 
of the telescope. The screw head is a circle ruled to degrees and minutes, 
and turns in front of a fixed vernier in the field of a reading microscope. One 
turn of the screw moves the web a certain number of seconds; then as there are 
