122 NOMOS. 



is a matter of necessity. The retrograde movements 

 of some comets, which was mentioned as the second 

 difficulty, may also be disposed of, and with far 

 greater facility. Indeed, all that is necessary is to 

 suppose that the currents surrounding these comets 

 are retrograde, that is, turned in the opposite direc- 

 tion to the ordinary course ; and it must of necessity 

 follow that the reactions between them and the 

 currents impinging upon them from the Sun must 

 issue in retrograde motion. 



It is with the satellites, also, as with the pla- 

 nets and comets; and these bodies must needs 

 move onwards in their orbits, and ro- 

 thiTiabora- ^te upon their axes, if it be assumed, 

 confer a the as mav we ll be done upon the premises, 

 movement of that they are surrounded by currents, and 



satellites. J J 



that converging currents stream from 

 their primaries upon them. It is clear, also, that 

 those among them which pursue a retrograde course 

 will be made to do this if the currents surrounding 

 them are retrograde as regards the common course. 



And if the planets and comets must move in their 

 orbits and rotate upon their axes in consequence of the 

 reactions which take place between the 

 e iabora. f Sun and them, it follows that the Sun him- 

 counrJor^he self must circulate and rotate. The Sun 

 movements himself must do this, because the attracting 



of the Sun. 



powers of the currents which proceed from 

 him to the planets and comets are intensified on the 

 side on which the direction of these currents coincides 



