Table 117. 



MISCELLANEOUS DATA WITH REGARD TO THE EARTH AND PLANETS.* 



Length of the seconds pendulum at sea 



1^^'el =/= 39.012540 4- 0.208268 sin2 ^ inches. 



= 3.251045 + 0.017356 sin- ip feet. 

 = 0.9909910 + 0.005290 sin- 9 metres. 

 Acceleration produced by gravity per sec- 

 ond per second mean solar time . . =^^=32.086528-1-0.171293 sin- 9 feet. 



= 977.9S86 -|- 5.2210 sin^ ^ centimetres. 



Equatorial semidiameter .... =« = 20925293 J- 409.4 feet. 



= 3963.124 -I- 0.078 miles. 

 = ^37797- zt 1-4.8 metres. 



Polar semidiameter =15 = 20855590 + 325.1 feet. 



= 3949.922 + 0.062 miles. 

 = 6356727 +99.09 metres. 



One earth quadrant =393775Si9+ 4927 inches. 



= 32814652 + 410.6 feet. 



Flattening =^~'^ = . 



^6214.896+0.078 miles. 

 = 10001816 + 125.1 metres. 



J00.205 + 2.964 



2 A^ 



Eccentricity = ~~ " = 0.006651018. 



Difference between geographical and geocentric latitude = — ^' 



= 688.2242" sin 2 cp— 1. 1 482" sin 4^ + 0.0026" sin 6 (p. 



Mean density of the Earth = 5.576 + o.oi6. 



Surface density of the Earth = 2.56 + 0.16. 



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

 and C the greater : 



C—A . I 



-TV = 0.0032652 I ^ -, • 



c -^ -■ 306.259' 



C — A = 0.001064767 Ed~ ; 

 A = B^ 0.325029 Ea- ; 

 C= 0.326094 Art- ; 

 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 



= 365.242199870 — 0.0000062124 ~ '' ^° mean solar days ; 



100 -' ' 



= 365 days 5 hours 48 minutes ^46.069 — 0.53675 ^Zli^'\ seconds. 



Length of sidereal month 



= 27.321661 162 — 0.00000026240 ^ . ~ ^°°9 days : 



100 -' ' 



= 27 days 7 hours 43 minutes ( 11.524 — 0.022671 ^~ ^^^ \ seconds. 



\ 100 / 



Length of synodical month 



= 29-530588435 — 0.00000030696 ~ '°? days ; 



= 29 days 12 hours 44 minutes ^2.841 —0.026522 ^-11^— —^ seconds. 

 Length of sidereal day = 86164.09965 mean solar seconds. 



'^■^■ — '^^^_ factor containing / in the above equations (the epoch at which the values of 

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



^ _ * Harkness, "Solar Parallax and Allied Constants." 



Smithsonian Tables. 



106 



