Section Ii.—Geometrical Astronomy and Astronomical Instruments.

By A. Fowler, A.R.C.S., F.R.A.S.

I. THE EARTH AND ITS ROTATION 41 II. THE EARTH’S REVOLUTION ROUND THE SUN 55 III. HOW THE POSITIONS OF THE HEAVENLY BODIES ARE DEFINED 65 IV. THE EARTH’S ORBIT 72 V. MEAN SOLAR TIME 78 VI. THE MOVEMENTS OF THE MOON 87 VII. MOVEMENTS OF PLANETS, SATELLITES, AND COMETS 98 VIII. ECLIPSES AND OCCULTATIONS 110 IX. HOW TO FIND OUR SITUATION ON THE EARTH 122 X. THE EXACT SIZE AND SHAPE OF THE EARTH 129 XI. THE DISTANCES AND DIMENSIONS OF THE HEAVENLY BODIES 139 XII. THE MASSES OF CELESTIAL BODIES 151 XIII. GRAVITATIONAL EFFECTS OF SUN AND MOON UPON THE EARTH 162 XIV. INSTRUMENTAL MEASUREMENT OF ANGLES AND TIME 171 XV. TELESCOPES 176 XVI. INSTRUMENTS OF PRECISION 198 XVII. ASTROPHYSICAL INSTRUMENTS 211