TABLES 668-569. 427 



TABLE 568. Length of Seconds Pendulum at Sea Level and for Different Latitudes. 



TABLE 569. Miscellaneous Geodetic Data. 



Equatorial radius = a = 6378206 meters; 



3963. 225 miles. 

 Polar semi-diameter = b = 6356584 meters; 



3949 . 790 miles. 



Reciprocal of flattening = -: = 295 . o 



Square of eccentricity = e 2 



a 2 -i* 



= 0.006768658 



6378388 =fc 1 8 meters; 

 3963-339 miles. 

 6356909 meters; 

 3949.992 miles. 



297.0 =*= 0.5 

 0.0067237 0.0000120 



Difference between geographical and geocentric latitude = </>' = 



688.2242" sin 20 1. 1482" sin 40 + 0.0026" sin 60. 



Mean density of the earth = 5.5247 =*= 0.0013 (Burgess Phys. Rev. 1902). 



Continental surface density of the earth = 2.67 \ TT i _ <;,> -icr> r>ar ttt 



Mean density outer ten miles of earth's crust = 2.40 ) Harkness - Se 



Constant of gravity, 6.66 X io~ 8 c.g.s. units. 



Rigidity = n = 8.6 X lo 11 c.g.s. units. \ A. A. Michelson, Astrophysical Journal, 39, 



Viscosity = e = 10.9 X io 16 c.g.s. units (comparable to steel), j p. 105, 1914. 



Moments of inertia of the earth; the principal moments being taken as A, B, and C, and C the greatest: 



C -A i 



7: = 0.00326521 = ; 



C 306.259 



C A = 0.001064767 <i 2 ; 

 A = B = 0.325029 Ea z ; 

 C = 0.326094 Ea 2 ; 

 where E is the mass of the earth and a its equatorial semi-diameter. 



SMITHSONIAN TABLES. 



