|Title:||Copy Extract On Smethwick'S Tube In Hand K|
|Ref:||8/57/1A-2B: 2A BLANK|
|Notes:||Another copy at 7/125.|
whose concavity is in such manner proportioned to the convexity, that the refracted rayes having passed the convexe side, thereof, falls upon the concave at right angles, and makes their passage through direct without a second refraction. Now if any glasse thus framed, be constituted the object glasse of a Perspective, and to this there be rightly prepared & adæquated an eye glasse, which may receive all such rayes at right angles, & transmitt them to the eye neerely parallel, then shall each of those two glasses so proportioned have but one single refraction, whereas in all others (whose arches incline) (the Conciall excepted) their converging rayes shall be twice in either glass refracted. According to this Methode & forme of a single refraction, is this Perspective fabricated, which if that Axiome in the Dioptricks be true, as undoubtedly it is, That refraction followes the Nature of Sines, then shall all converging Rayes for 15. degrees on each side the Axis be physically united into one point or focus. And (seing that not above the 1/5 of those degrees are here needfull) to all imaginable sense & purpose, shall this projection be nothing different from the Elipsis itself in the convexity, as it is the same, & doth most exactly agree in the concavity. But how farre this is or may be promoted for the better discovery of all visible & luminous bodies, & how farre it differs from all other heretofore practised, is submissively lefft to the determination of a future and indifferent examination.