36 



in an obliquity of 66 degrees 30 minutes, (the same 

 which given t@ the sails of a windmill, occasions its most 

 forcihle conversion) the sun's rays striking against the 

 oblique hemisphere, as the wind against ihe sails of a 

 windmill, keep it off, and at the same time make it turn 

 oil its own axis. The ether being a resisting medium, 

 and the atmosphere (ike the oars of a hoat) striking, 

 therein, urges it into a progressive motion. Meantime 

 its own gravity inclines it to the sun's centre, and of 

 course keeps it in equilibrio, with the repelling rays. 



" It is supposed likewise, that the plane of the earth's 

 orbit, is in winter in or near the sun's axis, whence the 

 rays are not so forcibly emitted; for which cause the 

 earth must then come nearer, the repelling force being 

 weaker. But in summer, being objected to the more 

 forcibly repelling rays, it must be driven to a farther 

 distance; whence its annual orbit must become ellip- 

 tical. 



" The earth's diameter being known, determines its dis- 

 tance from the sun. For as the diameter is 7.967, the 

 periphery 25031, which multiplied by the number of its 

 revolutions 36,525, gives for its orbit 9,142,572: and 

 as it moves through this orbit merely by the impulse of 

 the solar rays, and as the gravitating force must necessa- 

 rily be e-; .;*.' to that'impelliijg force ; so while it rolls 

 onward o/.; uile, it is attracted another. Consequently 

 the preceu :; orbit being doubled, by the gravitating 

 force, make in all 18/285,144. The semi-diameter of 

 this is the distance of the earth from the sun: which 

 therefore is neither more nor less than 2,910,364 

 miles. 



" In the same manner we find the distance of Venus 

 from the sun, t<> b" 1,790,684 miles: that of Mars, 

 5,473,690 ; that of Jtipiter^ 34,520,432 : that of Sa- 

 turn, "85,727,320 : and that of Mercury, 700,758. 



" -And as these distances are fur less than those assigned 

 2 



