Page:Sir William Herschel, his life and works (1881).djvu/164

142 "I cannot help reflecting with some pleasure on the discovery of an analogy which shows that a certain uniform plan is carried on among the secondary planets of our solar system; and we may conjecture that probably most of the satellites are governed by the same law; especially if it be founded on such a construction of their figure as makes them more ponderous towards their primary planets."

I believe the last suggestion to have been the first statement of the possible arrangement of matter in satellites, which was afterwards so forcibly maintained by in his theory of the moon. researches show the consequences of such an arrangement, although they do not prove its existence.

It should be recorded that the explanation which is to-day received of the belts and bands upon Jupiter, is, I believe, first found in memoir on Venus (1793). His memoir of 1797, on the changeable brightness of the satellites of Jupiter, has already been referred to. The times of the rotation of the satellites on their axes was first determined by from these observations, which