Spectroscope, its use explained, 147 used on pole-star, 19 to observe Saturn's rings, 147 Spiral nebulæ, 31 Stability, of Saturn's rings, 145 of Solar System, 210 Standards, time, of the world, 111 table of, 130 "Standard" time, explained, 127 Star-catalogue, general photographic, 102 Star-clusters, photography of, 98 Star-distances 94, 106 measured with heliometer, 158 Rutherfurd, 94 Star magnitudes, 91 Star-motion, toward us, 21 Star-tables, astronomical, 118 Stars, variable, 42 St Gothard railway, tunnels, 220 Sun, newspaper, the moon hoax, 201 SUN-DIAL, HOW TO MAKE A, 69 SUN'S, DESTINATION, 210 distance, compared with star distance, 97 measured with Eros, 67, 106 motion, apex of, 221 Sun-spots, discovered by Galileo, 49 _Systema Saturnium_, Huygens, 143 Telescope, clock, 175 at Paris Exposition, 176, 180 double, for photography, 86 equatorial, explained, 170 first used by Galileo, 49 motion of, 87 mounting great, 170 unmoving, for polar photography, 197 TEMPORARY STARS, 37 in Andromeda nebula, 28, 29, 45 in Aquila, 40 in Cassiopeia, 40 in Perseus, 46 in Scorpio, 39 their number, 38 theory of, 42 Time, correct, determined astronomically, 113 differences between different places, 121 TIME STANDARDS OF THE WORLD, 111 standards of the World, table of, 130 system, in New York, 120 zones, explained, 128 Trails, photographic, 191 Transit, for determining clock error, 118 Tycho Brahe, his temporary star, 40 Ulugh Beg, early star-catalogue, 21 Undulatory theory, of light, 19, 148 Universe, theories of, 34, 53, 56 Uranus, discovered by Herschel, 59, 142 Use of occultations, 166, 167 Uses of astronomy, practical, 112 Variable stars, 42 in Argo, 205 Vega, future pole-star, 187 Visibility of stars, in day-time, 191 Vision, phenomenon of, 20, 149 Washington, its longitude first determined, 168 Waves, explained, 148 of light, 20, 148 Wilkes, at Naval Observatory, Washington, 169 Wilkins, imaginary voyage of, 208 Witt, discovers Eros, 66, 105 Wolf, M, invents asteroid photography, 104 measures Pleiades, 11 World's time standards, table of, 130 Yale College, Pleiades measured at, 15 Zones, time, explained, 128 TRANSCRIBER'S NOTE Italic text is denoted by _underscores_. Fractions in the two tables on pg 74 and pg 78 are displayed in the form "a-b/c" as 4-1/2 or 2-7/16 for example. The original text in the tables used the form "a b-c". A few other basic fractions in the text such as ½ and ⅖ are displayed in this same form in the etext. There is only one Footnote in this book, with its anchor on pg 69. It has been placed at the end of the chapter containing the anchor.