Letters on Astronomy: Addressed to a Lady; in which the Elements of the Science are Familiarly Explained in Connexion with Its Literary History |
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Page 17
... measuring angles . ( See Fig . 1 , page 18. ) A line drawn from the centre to the circumference of a circle is ... measured by an arc included between Fig . 1 . K B two radii . Thus 2 * DOCTRINE OF THE SPHERE . 17.
... measuring angles . ( See Fig . 1 , page 18. ) A line drawn from the centre to the circumference of a circle is ... measured by an arc included between Fig . 1 . K B two radii . Thus 2 * DOCTRINE OF THE SPHERE . 17.
Page 18
... measured by A B. But this arc is the same part of the smaller circle that EF is of the greater . The arc A B , therefore , con- tains the same number of degrees as the arc E F , and either may be taken as the measure of the angle A C B ...
... measured by A B. But this arc is the same part of the smaller circle that EF is of the greater . The arc A B , therefore , con- tains the same number of degrees as the arc E F , and either may be taken as the measure of the angle A C B ...
Page 19
... measured by an arc of an- other great circle , of which the angular point is the pole , being the arc of that great circle intercepted be- tween those two circles . In order to fix the position of any place , either on the surface of ...
... measured by an arc of an- other great circle , of which the angular point is the pole , being the arc of that great circle intercepted be- tween those two circles . In order to fix the position of any place , either on the surface of ...
Page 20
... measured on a vertical circle . The azimuth of a body is its distance , measured on the horizon , from the meridian to a vertical circle pass- ing through that body . The amplitude of a body is its distance , on the ho- rizon , from the ...
... measured on a vertical circle . The azimuth of a body is its distance , measured on the horizon , from the meridian to a vertical circle pass- ing through that body . The amplitude of a body is its distance , on the ho- rizon , from the ...
Page 21
... measured on a ver- tical circle passing through that body . It is the com- plement of the altitude . The axis of the ... measures of time . The latitude of a place on the earth is its DOCTRINE OF THE SPHERE . 21.
... measured on a ver- tical circle passing through that body . It is the com- plement of the altitude . The axis of the ... measures of time . The latitude of a place on the earth is its DOCTRINE OF THE SPHERE . 21.
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Common terms and phrases
angle appear ascertain astronomers atmosphere attraction axis called celestial centre circle comet conjunction constellation degrees diameter direction discovery disk distance diurnal motion doctrine double stars earth ecliptic equal equator equinox exhibited fact fixed stars force Galileo globe gravity greater greatest half Halley's comet heavenly bodies heavens Hence Herschel horizon hundred inferior conjunction instrument John Herschel Jupiter Kepler latitude laws length less light longitude lunar lunar eclipse magnitude measure Mercury meridian meteors millions of miles minutes moon moon's motion move Nature nearer nearly node objects observations opposite orbit parallax passing perihelion period phenomena planetary planets pole respect revolve right ascension ring round satellites Saturn seen shadow side space spectator sphere sun's superior planets supposed surface telescope thousand tides tion truth Tycho Tycho Brahe universal gravitation Uranus velocity Venus vernal equinox visible west to east