Page:Philosophical Transactions - Volume 001.djvu/78

 then he will observe, whether he can see them appear upon the Belt, as upon a darker ground, especially, the third of them, which is sensibly greater, and more Luminous, than the rest. He hopeth also, that in time, the shadow of Saturns Moon will be seen upon Saturn, although we are yet some years to stay for it, and to prepare also for better Glasses.

From this rare Observation, he inferrs the Proportion of the Diameter of the Satellites to that of Jupiter; and judgeth, that no longer doubt can be made of the turning of these 4. Satellites, or Moons about Jupiter, as our Moon turns about the Earth, and after the same way as the rest of the Celestial Bodies of our Systeme do move: whence also a strong conjecture may be made, that Saturns Moon turns likewise about Saturn.

Hence he also taketh occasion to intimate, that we need not scruple to conclude, that if these two Planets have Moons wheeling about them, as our Earth hath one that moves about it, the conformity of these Moons with our Moon, does prove the conformity of our Earth with those Planets, which carrying away their Moons with themselves, do turn about the Sun, and very probably make their Moons turn about them in turning themselves about their Axis; and also, that there is no cause to invent perplex'd and incredible Hypotheses, for the receding from this Analogie since (saith he) if this be truth, the Prohibitions of publishing this doctrine, which formerly were caused by the offence of Novelty, will be laid aside, as one of the most: zealous Doctors of the contrary Opinion hath given cause to hope, witness Eustachius de Divinis, in his Tract against Monsieur Hugen's Systeme of Saturn, p. 49. where we are inform'd, that that learned Jesuit, P. Fabry, Penitentiary of S Peter in Rome, speaks to this purpose: