Arcturus, spectrum, [373] [383];
radial movement, [387]
Argelander, Bonn Durchmusterung,[ 32], [423];
solar motion,[ 39]
centre of Milky Way,[ 40]
comet of 1811 [100]
Aristotle, description of a comet, [350]
Arrhenius, light-pressure theory of comets, [348]
Asten, movements of Encke's comet,[ 94]
Asteroids, so designated by Herschel,[ 75]
Astronomical circles, [121] [122]
Astronomical physics, [7],[141] [142]
Astronomical Society founded, [6];
Herschel its first President,[ 14]
Astronomy, classification, [1];
popularity and progress, [5]
in United States, [6]
in Germany,[ 28]
practical reform,[ 32]
of the invisible,[ 42]
physical, [141]