Thoughts on the fuppofcd Variations, &c. 3 1 1 



Iieniifpheres on each fide of their orbit, which always divides 

 the body in the middle, were put in perfeft equilibrium. 



Our earth as well as every other planet is carried round the 

 fun by the radius veaor, (the ftraight line drawn from the 

 planet to the fun,) as the centripetal forces continually ad 

 according to that line, or in a perpendicular direftion. But 

 this line of attraolion, during the revolution of the earth, on 

 account of the continual paralleliim of its axis, forms with 

 the latter verv dilferent auirles; and yet the duration and pe- 

 ciod of the rotation remain unaltered. This great difference 

 in the angles has therefore no influence whatever in this re- 

 fpc6l; antfit appears that there exirts fome other great power 

 capable of prefcrving the direftion and inclination of the axis 

 unchanfred, and which, in my opinion, may be afcribed alfo 

 to the lun. 



Our earth during its annual courfe, revolving from weft to 

 ea(t, turns in fucceflion every part of its furface to the fuji, 

 and at the fame time revolves from eaft to weft on a line 

 pafling tlirough its centre perpendicular to the plane of its 

 orbit ;"or paffing through the poles of the ecliptic, as a fecond 

 axis, for the purj^ofe of^onftantly maintaining the parallelifm 

 of its proper axis of rotation. Now, if it can be admitted 

 that the fun produces this revolution of the earth in the plane 

 of the ecliptic correfponding with the arch of its orbit, this, 

 in my opinion, is a more natural explanation of the paral- 

 lelifn'i of the earth's axis than when it is confidered merely 

 as the confequeiice of a certain eftablifhed pofition of it inca- 

 pable of alteration; as this principle is applicable only to the 

 action of mechanical powers on bodies that move and revolve 

 in a ftraight line ; whereas the fun is continually drawing 

 our earth from the (traight line, and carrying it around it iu 

 a cruciform manner. 



According to this theory, we may eafily conceive how it is 

 poftible that a planet the axis of which, by the equilibrium of 

 its heterogeneous parts eftabliftied at its creation, is put into 

 a certain diredion, fubjefted to certain laws, may, by the 

 powerful influence of the fun, be made to deviate from it fo 

 tiiat its axis fliall aflumc another portion and inclination, or, 

 in other words, chaiisre its poles. 



Our earth, in coniequence of flow or fudden variations of 

 the iait kind, would produce in the heavens the following 

 phicuomciKi : 



lit, 11 the inflinalion of the earth's axis fliould change, 

 the Zodiac would be (till the fame, but the obliquity of the 

 fcliiiiic would be greater or lei's; the equator would pals 

 ihruugli oilier liars; and, in this tale, all countries lying 



LJ 4 under 



