PORTION OF 1HE COSMOS. THE SOLAR DOMAIN. 351 



in either of the two inferior planets Mercury or 

 Venus. 



Earth. 



The mean distance of the Earth from the Sun is 12032 

 times greater than the Earth's diameter therefore 20682000 

 German, or 82728000 English, geographical miles, this 

 quantity being considered uncertain to about 90000 German, 

 or 360000 English, geographical miles, or -^th of its 

 amount. The time of the sidereal revolution of the Earth 

 round the Sun is 365 d . 6 h . 9 m . 10 s . 7496. The excentricity 

 of the Earth's orbit amounts to 0-01679226, its mass 

 is '3-5 9*55 1, and its density in proportion to water is as 5 '44 

 to 1. BesseFs investigation of ten measurements of degrees 

 gave the terrestrial ellipticity -^-^-mr't the length of a 

 German geographical mile of 15 to a degree at the equator 

 3807*23 toises ; and the equatorial and polar diameters 

 respectively 1718'9 and 1713'! such miles, or 6 87 5 -6 and 

 6852'4 English geographical miles (Kosinos, Bd. i. S. 421, 

 Anm. 100 ; Eng. ed. p. xlii. Note 130). I confine myself 

 here to numerical data of figure and motion ; all that relates 

 to the physical constitution of the Earth is reserved for the 

 last i. e. the telluric portion of the Cosmos. 



The Earth's Satellite. 



The mean distance of the Moon from the Earth is 51800 

 German, or 207200 English, geographical miles; its side- 

 real period of revolution 27 days, 7 hours, 43 minutes, and 

 11*5 seconds; the excentricity of its orbit 0-0548442 ; its 

 diameter 454 German, or 1816 English, geographical miles, 



