IOS TABLE 89. 



MISCELLANEOUS DATA WITH REGARD TO THE EARTH AND PLANETS.* 



Length of the seconds pendulum at sea level =7=39.012540+0.208268 sin 2 finches. 



=3.251045+0.017356 sin 2 feet. 

 =0.9909910+0.005290 sin 2 metres. 



Acceleration produced by gravity per second 



per second mean solar time . . . =^=32.086528+0.171293 sin 2 feet. 



=977.9886+5.2210 sin 2 centimetres. 



Equatorial radius =0=6378206 metres ; 



3963.225 miles. 

 Polar semi-diameter ==6356584 metres ; 



3949.790 miles. 



Reciprocal of flattening= - =295.0 



a b ^ 



S. 



Square of eccentricity =**= -^ =0.006768658 



6378388+18 metres; 

 39 6 3-339 miles. 

 6356909 metres ; 

 3949.992 miles. 



297.0+0.5 



0.0067237+0.0000120. 



Difference between geographical and geocentric latitude= 00'= 



688.2242 // sin 2 01.1482" sin 4 0+0.0026" sin 60. 



Mean density of the Earth=5.5247o.ooi3 (Burgess Phys. Rev. 1902). 



Continental surface density of the Earth =2.67 \ Harkness 

 Mean density outer ten miles of earth's crust=2.4O j 



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

 C the greater: 



C-A , i 



=0.00^2652 1 = 7 ; 



C 306.259' 



C -4 =0.00 1064767 Ea*\ 

 A =^=0.32 5029 Ea z -, 

 C =0.326094 a 2 ; 

 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=365.242i9987O 0.0000062124 ^-mean solar days; 



=365 days 5 hours 48 minutes (46.0690.53675-^-^- J seconds. 



Length of sidereal month 



: 27.32i66i 162 0.00000026240 days; 



=27 days 7 hours 43 minutes ( 1 1.5240.022671 J seconds. 



Length of synodical month 



, ,t 1800, 

 =29.530588435-0.00000030696 ^ days; 



=29 days 12 hours 44 minutes (2.8410.026522 - 1 seconds. 

 Length of sidereal day = 86164.09965 mean solar seconds. 



N. B. The factor containing/ 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. 



