Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/242

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Dialogue. II.
217

remotiores, in minori circulo feruntur? [scilicet:] Why are those near the Æquinoctial carried about in a greater circle, and those which are remote in a lesser?

Salv.To imitate the starry Sphere, in which those nearest to the Æquinoctial, move in greater circles, than the more remote.

Simpl.Quarè Pila eadem sub Æquinoctiali tota circa centrum terræ, ambitu maximo, celeritate incredibili; sub Polo verò circa centrum proprium, gyro nullo, tarditate supremà volveretur? [That is:] Why is the same ball under the Æquinoctial wholly turned round the centre of the Earth in the greatest circumference, with an incredible celerity; but under the Pole about its own centre, in no circuite, but with the ultimate degree of tardity?

Salv.To imitate the stars of the Firmament, that would do the like if they had the diurnal motion.

Simpl.Quare eadem res, pila v. g. plumbea, si semel terram circuivit, descripto circulo maximo, eandem ubique non circummigret secundùm circulum maximum, sed translata extra Æquinoctialem in circulis minoribus agetur? [Which speaketh thus:] Why doth not the same thing, as for example, a ball of lead turn round every where according to the same great circle, if once describing a great circle, it hath incompassed the Earth, but being removed from the Æquinoctial, doth move in lesser circles?

Salv.Because so would, nay, according to the doctrine of Ptolomey, so have some fixed stars done, which once were very near the Æquinoctial, and described very vast circles, and now that they are farther off, describe lesser.

Sagr.If I could now but keep in mind all these fine notions, I should think that I had made a great purchase; I must needs intreat you, Simplicius, to lend me this Book, for there cannot chuse but be a sea of rare and ingenious matters contained in it.

Simpl.I will present you with it.

Sagr.Not so, Sir; I would not deprive you of it: but are the Queries yet at an end?

Simpl.No Sir; hearken therefore. Si latio circularis gravibus & levibus est naturalis, qualis est ea quæ fit secundùm lineam rectam? Nam si naturalis, quomodo & is motus qui circum est, naturalis est, cùm specie differat à recto? Si violentus, quî fit, ut missile ignitum sursum evolans scintillosum caput sursùm à terrâ, non autem circum volvatur, &c. [Which take in our idiom:] If a circular lation is natural to heavy and light things, what is that which is made according to a right line? For if it be natural, how then is that motion which is about the centre natural, seeing itdiffers