Observations of the changeable brightness of the satellites of Jupiter : and of the variation in their apparent magnitudes; with a determination of the time of their rotatory motions on their axes. To which is added, a measure of the diameter of the second satellite, and an estimate of the comparative size of all the four. By William Herschel, LL.D. F.R.S. From the Philosophical transactions. - Herschel, William, (1797)