to admit, if the sun were at rest; and, to remove this objection, the necessity for admitting its motion ought to be well established.
Theoretical 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 center; and those who like to indulge in fanciful reviews of the heavens, might easily build a system 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 supposed to move about the nebula in Orion.[1] But, setting aside the extravagant idea of making this luminous spot a center 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 Paper,[2] that the possibility of a solar motion has also been shown from theoretical principles by the late Dr. Wilson of Glasgow; and its probability afterwards, from reasons of the same nature, by Mr. De la Lande. The rotatory motion of the sun, from which he concludes a displacing of the solar center, 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 intirely unacquainted with the cause of the rotatory motion, the solar
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