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126 as the Revolution of Jupiter with repect to that of the Earth. He proves, that as the Planets make their Revolutions in Elipis's, and conequently being at a much greater Ditance one from the other in their Aphelia, and a little nearer in their Perihelia; the Earth's Velocity, for Intance, ought to be greater, when 'tis nearer Venus and Mars, becaue the Fluid that carries it along, being then more pres'd, ought to have a greater Motion; and yet 'tis even then that the Earth's Motion is lower.

proves that there is no uch Thing as a celetial Matter which, goes from Wet to Eat, ince the Comets travere thoe Spaces, ometimes from Eat to Wet, and at other Times from North to South. fine, the better to reolve, if poible, every Difficulty, he proves, and even by Experiments, that 'tis impoible there hould be a Plenum; and brings back the Vacuum, which Aritotle and Des Cartes had banih'd from the World.

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