Astronomical motions on which our time is founded. -- Reasons for selecting the sidereal day as a basis for our 24-hour day. -- Year of the seasons shorter than the zodiacal year. -- Precession of the equinoxes. -- Earth's rotation most uniform motion known to us. -- Time Stars and Transits. -- Local time. -- The date line. -- Standard time. -- Beginning and ending of a day. -- Proposed universal time. -- Clock dial for universal time and its application to business. -- Next great improvement in clocks and watches indicated. -- Automatic recording of the earth's rotation. -- Year of the seasons as a unit for astronomers. -- General conclusions. The mystery of time encloses all things in its folds, and our grasp of its infinite bearings is measured by our limitations. As there are no isolated facts in the Universe, we can never get to the end of our subject; so we know only what we have capacity to absorb. In considering the foundation on which all our time measuring is based, we are led into the fringe of that Elysian field of science--astronomy. A science more poetical than poetry--more charming than the optimistic phantasies of youth. That science which leaves our imagination helpless; for its facts are more wonderful than our extremest mental flights. The science of vastness and interminable distances which our puny figures fail to express. "The stars sang together for joy," might almost be placed in the category of facts; while the music of the spheres may now be considered a mathematical reality. Our time keeping is inevitably associated with these motions, and we must select one which has periods not too long. That is, no _continuous_ motion could be used, unless it passed some species of milestones which we could observe. Consequently, our clocks do not--in the strict sense--measure time; but are adjusted to _divide_ periods which they do not determine. We are constantly correcting their errors and never entirely succeed in getting them to run accurately to _periods of time_ which exist entirely outside of such little things as men and clocks. So a clock is better as it approximates or bears a regular _relation_ to some motion in nature. The sidereal clock of the astronomer _does_ run to a regular motion; but our 24-hour clocks _do not_, as we shall see later. Now consider the year, or the sun's apparent motion in the Zodiac, from any given star around to the same one again. This is altogether too long to be divided by clocks, as we cannot make a clock which could be depended on for anywhere near a year. The next shorter period is that of a "moon." This is also a little too long, is not easily observed, and requires all sorts of corrections. Observations of the moon at sea are so difficult and subject to error that mariners use them only as a last resort. If a little freedom of language is permissible, I would say that the moon has a bad character all around, largely on