CONTENTS XI 



rr Section XL GEODETIC AND ASTRONOMICAL TABLES -,-, 



Table Page 



161. Geodetic and astronomical constants 481 



162. Length of one degree of the meridian 482 



163. Length of one degree of the parallel 483 



164. Distribution of water and land in various latitude belts 484 



165. Scale variation for standard map projections 485 



166. Radius of curvature on a polar stereographic projection 486 



167-168. Acceleration of gravity (explanation) 488 



167. Acceleration of gravity at sea level 491 



168. Relative acceleration of gravity at sea level 493 



169. Ephemeris of the sun 495 



170. Solar altitude and azimuth 497 



171-174. Duration of daylight, civil twilight, and astronomical twilight 



(explanation) 506 



171. Duration of daylight 507 



172. Duration of civil twilight 513 



173. Duration of astronomical twilight 517 



174. Daylight and twilight for southern latitudes 520 



Index 521 



U>& 



lw A-" 



