t of the circumference of a circle, or 90 deg..
QUADRATURE, a position of the moon or other body when 90 deg. from
the sun.
RADIANT POINT, that point of the heavens from which meteors seem
to diverge, 118.
RADIUS-VECTOR, an imaginary line joining the sun and a planet or
comet in any part of its orbit.
RAIN, weight of, 249.
REFLECTING TELESCOPE, 44.
REFRACTING TELESCOPE, 43.
REFRACTION, a bending of light by passing through any medium, as
air, water, prism.
RETROGRADE MOTION, the apparent movement of a planet from east
to west among the stars.
REVOLUTION, the movement of bodies about their centre of gravity.
ROTATION, the motion of a body around its axis.
SATELLITES, smaller bodies revolving around planets and stars.
SATURN, elements of, 167; revolution of, 168; rings of, 169;
decreasing, 171; nature of, 171; satellites of, 172.
SEASONS, of the earth, 102; of other planets, 105.
SELENOGRAPHY (_lunography_), a description of the moon's
surface.
SIGNS OF THE ZODIAC, the twelve equal parts, of 30 deg. each, into
which the zodiac is divided.
SOLAR SYSTEM, view of, 100, 177.
SOLSTICES, those points of the ecliptic which are most distant from
the equator. The sun passes one about June 21st, and the other
about December 21st, giving the longest days and nights.
SPECTROSCOPE, 46.
SPECTRUM OF SUN AND METALS, 50.
STARS, chemistry of, 28; distance of, 70-73; mode of naming, 196;
number of, 210; double and multiple, 210; colored, 214; clusters
of, 215; variable, 220; temporary, new, and lost, 223; movements
of lateral, 226; in line of sight, 269.
STATIONARY POINTS, places in a planet's orbit at which it has no
motion among the stars.
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STELLAR SYSTEM, the, 195.
SUMMARY OF RECENT DISCOVERIES, 269.
SUN, fall of two meteoric bodies into, 19; light from contraction
of, 20; as seen from planets, 79; corona, 81; hydrogen flames of, 84;
condition of, 89; spots, 90; experiments, 95; apparent path among
the stars, 111; power of, 250.
SYMBOLS USED IN ASTRONOMY, 275.
TELESCOPE, refracting, 43; reflecting, 44; Cambridge equatorial, 46.
TELESCOPIC WORK, clusters, 210; double stars, 212.
TEMPORARY STARS, 223.
TERMINATOR, the boundary-line between light and darkness on the
moon or a planet.
TIDES, 146.
TRANSIT, the passage of an object across some fixed line, as the
meridian, or between the eye of an observer and an apparently
larger object, as that of Mercury or Venus over the disk o