£32 On the Motion of the Sun and Solar System. 



consequences hereafter to be drawn from a solar motion, 

 when established, seem to contradict the very intention for 

 which it is to be introduced. The chief object in view,- 

 when a solar motion was proposed to be deduced from ob- 

 servations of the proper motions of stars, was to take away 

 many of these motions by investing the sun with a contrary 

 one. But the solar motion, when its existence has been 

 proved, will reveal so many concealed real motions, that 

 wc shall have a greater sum of them than it;would be ne- 

 cessary to admit, if the sun were at rest ; and, to remove 

 this objection, the necessity for admitting its motion ought 

 to be well established. 



llicoret'ical Considerations. 



A view of the motion of the moons, or secondary planets, 

 round their primary ones, and of these again round the sun, 

 may suggest the idea of an additional motion of the latter 

 round some other unknown centre; and those who like to 

 indulge in fanciful reviews of the heavens, might easily 

 build a svstem upon hypotheses not altogether without 

 some plausibility in their favour. Accordingly we find that 

 Mr. Lambert, in a work which is full of the most fantastic 

 imaginations, has framed a system wherein the sun is sup- 

 posed to move about the nebula in Orion*. But, setting 

 aside the extravagant idea of making this luminous spot 

 a centre of motion, it must certainly be admitted that the 

 solar motion itself is at least a very possible event. 



I have already mentioned, in a note to my former paperf, 

 that the possibility of a solar motion has also been shown 

 from theoretical principles by the late Dr. Wilson, of Glas- 

 gow ; and its probability afterwards, from reasons of the 

 same, nature, bv Mr. de la Lande. The rotatory motion of 

 the sun, from which he concludes a displacing of the solar 

 centre, must certainly be allowed to indicate a motion of 

 translation in space ; for though it may be possible, it'does 

 not appear probable, that any mechanical impression should 

 have given the former, without occasioning the latter. 

 But, as we are entirely unacquainted with the cause of the 

 rotatory motion, the solar translation in space from theore- 

 tical reasons, can only be admitted as a very plausible hy- 

 pothesis. 



It would be worth while for those who have fixed instru- 

 ments, to strengthen this argument by observing the stars 



* See Si/sliwe du JVoiidc de Mr. Lambert, p. 152 and US. 

 f See riiil. Trans, for the year 1763. p. :ii:3. 



which 



