Tables 668-S69. 42 7 



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 



a — b 



= 295-0 



(j2 _ J2 



Square of eccentricity = e^ = — = 0.006768658 



C-j 63783S8 =t 18 meters; 



&• 3963-339 miles. 



^ 6356909 meters; 



■* 3949.992 miles. 



^ 297.0 =4=0.5 



I 



S.' 0.0067237 =fc 0.0000120 



Co Co 

 8 • 



Difierence between geographical and geocentric latitude = if> — <j)' = 



688.2242" sin 2<p — 1.1482" sin 4<j} + 0.0026" sin 6<p. 



Mean density of the earth = 5. 5247 =fc 0.0013 (Burgess Phys. Rev. 1902). 



Continental surface density of the earth = 2.67 

 Mean density outer ten miles of earth's crust 



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



2 ,■ Harkness. See also page 423. 

 Mass = 5.997 X 10" c.g.s. units. 



Rigidity = n = 8.6 X 10" c.g.s. units. ) A. A. Michelson, Astrophysical Journal, 39, 



Viscosity = e = 10.9 X loi^ c.g.s. units (comparable to steel). J p. 105, 1914. 



Moments of inertia of the earth; the principal moments being taken as ^, 5, and C, and C the greatest 



C -A ^ I 



— p; — = 0.00326521 = — ; 



C 306.259 



C — A — 0.001064767 Ea^; 

 A = B = 0.325029 Ea^; 

 C = 0.326094 Ea^; 

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



Velocity ol Compresslonal Earthquake Waves and Elastic Constants of Rocks. 



Velocityt 



7.17 km/sec. 



7-59 



8.42 



9.62 

 11.07 

 12.40 

 12.95 



t Weichert. 



Poisson's Ratio.t 

 0.258 

 •273 

 .272 

 .274 

 .270 



Smithsonian Tables. 



