Laurence, Lionel · London, School of Optics · leaf 64
the normal, with which itmakes a larger angle than before refraction. In Fig. 47, let A B be the 52 GENERAL AND PRACTICAL OPTICS incident and B C the refracted ray. As the angle of incidence is increased,so the corresponding angle of refraction becomes still larger. Hence if theray AB be incident… … Fig. 47. this result is termed the critical angle, because the slightest further increaseof it prevents the ray from passing out of the denser medium. If the incidentray be A B it is reflected as B C, and internal reflection takes place. Thisis termed total to distinguish it from ordinary…
Optics
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-193-113.webp)
