Practical Talks by an Astronomer

actually Andromeda nebula ascer astron astronomical observations attraction bright called catalogue celestial celestial pole centre changes chronometer circle clock constellation cosmic course dial direction discovery disk distance earth exact exposure eye-end fact faint field of view Galileo graphic telescope Greenwich heavenly bodies heavens heliometer Herschel's Hipparchus important inches instru instrument interest Jupiter Keeler known large number latitude lens light longitude mark means measure ment meridian meridian circle method minor planets moon motion moving nebula night noon object observatory observer's obtain once orbit ordinary parallax pass photographic plate Pleiades polar axis polar motion pole position possible precision problem ring rotation Saturn scientific seen semi-lenses sextant shadow sidereal simply solar system space spectroscope spiral stellar stellar distances sun-dial surface telescope telescope's temporary star things tion to-day tube turning Uranus visible watch waves whole YERKES OBSERVATORY York