lOS Table 89. 



MISCELLANEOUS DATA WITH REGARD TO THE EARTH AND PLANETS.* 



Length of the seconds pendulum at sea level =/=39.oi2540+c.2o8268 sin'^ (finches. 



=3.251045+0.017356 sin^ (pieet. 

 =^0.9909910+0.005290 sin^ metres. 



Acceleration produced by gravity per second 



per second mean solar time . . . ^^=32.086528+0.17 1293 sin^0 feet. 



=977.9886 + 5.2210 sin^0 centimetres. 



Equatorial radius =^^6378206 metres ; 



3963.225 miles. 

 Polar semi-diameter =^=6356584 metres ; 



3949.790 miles. 



Reciprocal of flattening= =295.0 



Square of eccentricity =^^= — j— =0.006768658 



6378388+18 metres; " 

 ^ 3963-339 miles. 

 ^ 6356909 metres; 

 ? 3949-992 miles. 



;s, 297.0 + 0.5 



S^ 0.0067237+0.0000120. 





Difference between geographical and geocentric latitude=0— 0'= 



688.2242" sin 2 0—1. 1482" sin40+o.oo26"sin60. 



Mean density of the Earth = 5.5247 + 0.0013 (Burgess Phys. Rev. 1902). 



Continental surface density of the Earth = 2.67 "l „ . 



Mean density outer ten miles of earth's crust = 2.40 j ^^ 'ness. 



Moments of inertia of the Earth; the principal moments being taken as A, B, and C, and 



C the greater: 



C-A . I 



— 7;— =0.00 ■526521 = — 7 ; 



C ^ •' 306.259 



C— .,4=0.001064767 Ea^; 



A—B—o.22i,02g£a^; 



C =0.326094 j5'a' ; 



where E is the mass of the Earth and a its equatorial semidiameter. 



Length of sidereal year= 365.2563578 mean solar days; 



=365 days 6 hours 9 minutes 9.314 seconds. 



Length of tropical year=365.242i99870— 0.0000062124-^^ — ^mean solar days; 



100 ■' 



=365 days 5 hours 48 minutes { 46.069—0.53675-^ — ^ ) seconds. 

 ^ 100 J 



Length of sidereal month 



_ - /c^ /: ^ /— 1800 , 



— 27. 32 1 661 162—0.00000026240 days: 



100 •' 



=27 days 7 hours 43 minutes ( 1 1.524—0.022671-^ j seconds. 



Length of synodical month 



= 29. 530 58843 5 —0.00000030696 days ; 



100 



=:29days i2hours44 minutes (2.841—0.0261522 j seconds. 



\ -' 100 / 



Length of sidereal day = 86164.09965 mean solar seconds. 



N- B. — The factor containing t in the above equations (the epoch at which the values of 

 the quantities are required) may in all ordinary cases be neglected. 



• Mostly from Harkness, " Solar Parallax and Allied Constants." 

 Smithsonian Tables. 



