Full text: Barrow, Isaac: Lectiones Opticæ & Geometricæ

17. Lect . VIII.

I QUæ radiis obveniunt à longinquo puncto manantibus, adc-
óque quaſi parallelis, ex reflectione peripheriam ad circula-
rem peractâ; ubinam & quouſque vel ſibimet ipſis occurrunt, vel ax-
em interſecant; quo loco radians oculo ubicunque conſtituto repræ-
ſentant, in poſtremis eſt diſſertatum. ad punctum jam accedimus ra-
dios ejiciens ſenſibiliter divergentes. Et hujuſmodi quidem puncto,
quanquam ſeu in obverſas circuli Convexas partes ſeu ad concavas
radiet communia pleraque ſymptomata conveniunt; tamen communi
fretus _Opticorum_ exemplo, præſertímque majoris evidentiæ causâ,
caſus iſtos diſtinctè proſequemur; illum fuſiùs imprimis, hunc aliquan-
to conciſiùs. ad rem.

II. In circuli BNP (cujus centrum C) convexum à puncto A
quilibet incidat radius AN, íſque reflectatur in NG; patet reflex-
um GN productum axi AC occurſurum. nam ductâ CNE patet
GN productum angulum ANC ſecare; nec non ideò trianguli
ANC baſin AC; puta in K; quo poſito.

III. Dico fore AC. AN : : KC. KN. Nam ducatur KH ad
CN parallela. eſt igitnr ang. KHN = CNP = CNK = NKH. hoc etiam è ſuperiùs generatim oftenſis conſectatur. adeóque NH
= NK. itâque cùm ſit AC. AN : : KC. HN. erit etiam AC. AN : : KC. KN.

IV. Corollarii loco notetur (ductâ CP) fore NH = NK; & triangula HNK, NCP aſſimilari; vel eſſe HK. HN : : NP. CN.

V. Porrò, conftantibus iiſdem, dico fore AC. KC : : ACq
- ANq . CNq. Nam eſt NP. CN + AN. CN = HK. HN + AN. CN = HK x AN. HN x CN = AN. HN

Waiting...

Note to user

Dear user,

In response to current developments in the web technology used by the Goobi viewer, the software no longer supports your browser.

Please use one of the following browsers to display this page correctly.

Thank you.

powered by Goobi viewer