el INDEX TO ASTRONOMY. 
Seyphoid, the, 26. 
Sextant, Hadley’s, 66. 
Shadows, projection of, 43; difference between 
shadows and shades, ib. ; shades and shadows 
upon plane surfaces and curved surfaces of 
elevation, 44; on hollow, straight, and curved 
surfaces, 48. 
Sight ruler, 60 ; vanes, 70. 
Sine, explanation of, 18. 
Solids, geometry of, 13 ; angular, 14; method of 
finding the projection of, 36. 
Sphere, the, 16. 
Spheroid, the, 27. 
Spirals, the, 26. 
Square, the, as a unit of measure to determine 
the superficial relations of figures, 9. 
Staves, levelling, 70. 
Stereometry, definition of, 1 ; explanation of, 13. 
Suardi’s eccentric compasses, 56. 
Surfaces of intersection, method of determining 
the outlines in horizontal and vertical pro- 
jection, 39. 
Surveying, 28; principal problem of, 31 ; differ- 
ent methods of, 31. 
Tangent, explanation of, 18. 
Telescope, the levelling, 69. 
Theodolite, the, 64. 
Topographical drawing, 33. 
Triangles, 3 ; properties proved by the equality 
of, 5; problems solved by, 6 ;* propositions 
proved by the similarity of, 7; trigonometrical 
rules for the solution of all cases of right- 
angled and acute-angled, 18; spherical, 20: 
rules for calculating spherical, 21. 
Trigonometry, plane, 17 ; spherical, 20; applica 
tion of, to geodesy, 22. 
Trochoid, the, 26. 
Unfolding or development of surfaces, 41. 
Vanes, sight, 70. 
Vernier, the, description of, 67. 
Wallace’s pantograph or eidograph, 57. 
Zollman’s instrument for determining angles, 62. 
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ALicgNMENTs, method of, 93, 173. 
Altitude, parallax in, 97. 
Amphiscii, the, 147. 
Annual parallax of a planet, 99. 
Anomaly, mean and true, 99. 
Antipodes, the, 146. 
Anteci, the, 146. 
Aphelion distance, 99. 
Apogee, definition of, 119. 
Apsides, line of, 107. 
Arabians, astronomy exclusively cultivated by 
them in the seventh century, 74. 
Aristarchus, the most celebrated of the Greek 
astronomers, 74. 
Armillary sphere, the, 76. 
Ascii, the, 147. 
Asteroids, the, 104; Moébius’s model for repre- 
senting the orbits of, 172. 
Astrognosy, practical, 173. 
Astrograph, the, 172. 
Astrology, founded by the Chaldeans, 74; dies 
away in the seventeenth century, 75. 
Astronomical instruments, 154; celebrated makers 
of, 155. 
Astronomy, definition of, 73 ; divisions and sub- 
divisions, ib. ; historical survey of, 74 ; spheri- 
eal, 76; theoretical, 97; physical, 123. 
Aurora, the, 144. 
Axis of the heavens, 85. 
Babylonians, length of the year determined by, 
74. 
Beer and Madler, general map of the moon, 133- 
137. 
Bessel, his investigations, 89 ; his measurements 
of a degree, 124. 
Biela’s comet, 143. 
652 
Brahe, Tycho, opposes the doctrines of Coperni- 
cus, 75. 
Cesar, Julius, introduces the Greek calendar, 
74150. 
Calendar, definition of the, 149; of the Greeks 
and Romans, 150 ; the Gregorian, 151 ; Russo- 
Grecian, 152; Jewish, Turkish, and French 
Republican, 153. 
Cancer and Capricorn, tropies of, 85. 
Celestial sphere, points, circles, and terms in the, 
76; apparent rotation of the, 79. 
Centrifugal force, 124. 
Chaldzans, introducers of the twelve signs, sun- 
dial, and eclepsydra, 74. 
Chinese, their early acquaintance with astronomy, 
74. 
Chronometers, 171. 
Cirele, properties of the, 97; the repeating and 
meridian, 162 ; crepuscular, 128. 
Clock, the wheel, 169 ; the mercurial, 172. 
Collimation, error of, 161. 
Colure, the solstitial, 107. 
Comets, influence of the resistance of the ether 
on the motion of, 131; statistics of various, 
142 ; speculations as to their habitableness, 149. 
Commutation of a planet, 98. 
Compensation pendulum of Harrison, 170. 
Compouné motion, 125. 
Constellations, names of forty-eight, as given by 
Hipparchus, 90, 91; names of the additional 
fifty-eight discovered in modern times, 92, 93. 
Copernicus, first presentation of his theory to the 
world, 75; his planetary system confirmed by 
Kepler, 103. 
Crepuscular cirele, 128. 
Cycle, solar and Junar, 151. 
