Full text: Barrow, Isaac: Lectiones Opticæ & Geometricæ

_XVII._ Ad lentem concavo convexam diverg.

Fig. 160,
161, 162.

_XVIII._ Ad lentem convexo-concavam converg.

Si Acadat extra BC, fiat AB - {R/I} AC. AB : : BC. BZ; ſin A
cadat inter B, & C; fiat AB + {R/I} AC. AB : : BC. BZ.

1. Jam cùm Z cadit extra DK, tum primò ſi {I/R} KZ & gt; DZ, fac
{I/R} KZ - DZ. DZ : : DK. DY, & cape DY adverſus A.

2. Secundò, ſi {I/R} KZ = DZ; imagò infinitè elongabitur.

3. Tertiò, ſi {I/R} KZ & lt; DZ, fac DZ - {I/R} KZ. DZ : : DK. DY; & ſume DY verſus A.

4. Sed quando Z inter D, & K cadit, fiat DZ + {I/R} KZ. DZ : :
DK. DY; & accipiatur DY verſus A.

Hiſce ſubnectam ſequentia; non contemnendum in _engyſcopicis_
uſum præ ſe ferentia _Problemata._

I. _Dati puncti propinqui A perfectam imaginem per lentem concavo-_
_convexam in aliud datum punctum Z lenti vicinius projicere._ (per-
fectam imaginem intelligo, quæ reſultat ex omnibus, quos ipſum A
diffundit, radiis in ipſa readunatis.)

20.1.

Fig. 163.

Fiat I - R. R : : AZ. ZB. & dividatur ZB in C, ut ſit CB. CZ : : I. R. tum centro C deſcribatur circulus EBF. item centro Z
intervallo quovis ZD (majoriquam ZB) deſcribatur circulus GDH; factum erit; nempe lens EFGH puncti A perfectam imaginem in
punctum Z projiciet.

Nota, datâ CB puncta A, Z è propoſitis facilè determinari.

In vitro, ſi CB = 15, erit {ZC = 9 \\ ZB = 24} & {AZ = 16. \\ AB = 40. Adnotetur etiam per lentem EGHF ad Z tendentes radios ad A
refringi.

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