Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/246

 stence before the common centre of gravity: so that it is not one centre alone, which is no other than indivisible point, and therefore of no efficacie, that can attract unto it grave matters; but that those matters conspiring naturally to unite, form to themselves a common centre, which is that about which parts of equal moment consist: so that I hold, that if the great aggregate of grave bodies were gathered all into any one place, the small parts that were separated from their whole, would follow the same, and if they were not hindered, would penetrate wherever they should find parts less grave than themselves: but coming where they should meet with matters more grave, they would descend no farther. And therefore I hold, that in the Cave full of air, the whole Vault would press, and violently rest it self onely upon that air, in case its hardness could not be overcome and broken by its gravity; but loose stones, I believe, would descend to the centre, and not swim above in the air: nor may it be said, that they move not to their whole, though they move whither all the parts of the whole would transfer themselves, if all impediments were removed.

That which remaineth, is a certain Errour which he observeth in a Disciple of Copernicus, who making the Earth to move with an annual motion, and a diurnal, in the same manner as the Cart-wheel moveth upon the circle of the Earth, and in it self, did constitute the Terrestrial Globe too great, or the great Orb too little; for that 365 revolutions of the Æquinoctial, are less by far than the circumference of the great Orb.

Take notice that you mistake, and tell us the direct contrary to what must needs be written in that Book; for you should say, that that same Copernican Author did constitute the Terrestrial Globe too little, and the great Orb too big; and not the Terrestrial Globe too big, and the annual too little.

The mistake is not mine; see here the words of the Book. Non videt, quòd vel circulum annuum æquo minorem, vel orbem terreum justo multò fabricet majorem. (In English thus:) He seeth not, that he either maketh the annual circle equal to the less, or the Terrestrial Orb much too big.

I cannot tell whether the first Author erred or no, since the Author of this Tractate doth not name him; but the error of this Book is certain and unpardonable, whether that follower of Copernicus erred or not erred; for that your Author passeth by so material an error, without either detecting or correcting it. But let him be forgiven this fault, as an error rather of inadvertencie, than of any thing else: Farthermore, were it not, that I am already wearied and tired with talking and spending so much time with very little profit, in these frivolous janglings and altercations, I could shew, that it is not impossible for a circle, though