Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/232

 sed to make it, vibrations successively more and more frequent; and consequently is able to bring a continual impediment to the plummet C; and for a proof that this is so, if we do but observe the thread AC, we shall see it distended not directly, but in an arch; and if instead of the thread we take a chain, we shall discern the effect more perfectly; and especially removing the gravity C, to a considerable distance from the perpendicular AB, for that the chain being composed of many loose particles, and each of them of some weight, the arches AEC, and AFD, will appear notably incurvated. By reason therefore, that the parts of the chain, according as they are neerer to the point A, desire to make their vibrations more frequent, they permit not the lower parts of the said chain to swing so far as naturally they would: and by continual detracting from the vibrations of the plummet C, they finally make it cease to move, although the impediment of the air might be removed.

The books are now come; here take them Simplicius, and find the place you are in doubt of.

See, here it is where he beginneth to argue against the diurnal motion of the Earth, he having first confuted the annual. Motus terræ annuus asserere Copernicanos cogit conversionem ejusdem quotidianam; alias idem terræ Hemisphærium continenter ad Solem esset conversum obumbrato semper averso. [In English thus:] The annual motion of the Earth doth compell the Copernicans to assert the daily conversion thereof; otherwise the same Hemisphere of the Earth would be continually turned towards the Sun, the shady side being always averse. And so one half of the Earth would never come to see the Sun.

I find at the very first sight, that this man hath not rightly apprehended the Copernican Hypothesis, for if he had but taken notice how he alwayes makes the Axis of the terrestrial Globe perpetually parallel to it self, he would not have said, that one half of the Earth would never see the Sun, but that the year would be one entire natural day, that is, that thorow all parts of the Earth there would be six moneths day, and six moneths night, as it now befalleth to the inhabitants under the Pole, but let this mistake be forgiven him, and let us come to what remaineth.

It followeth, Hanc autem gyrationem Terræ impossibilem esse sic demonstramus. Which speaks in English thus: That this gyration of the Earth is impossible we thus demonstrate. That which ensueth is the declaration of the following figure, wherein is delineated many descending grave bodies, and ascending light bodies, and birds that fly to and again in the air, &c.

Let us see them, I pray you. Oh! what fine figures,