An introduction to the science & practice of photography (1888)
Jones, Chapman · London : Iliffe & Son · leaf 86
other of a different density, it is turned from its original path, it is " refracted," unless it impinges perpendicularly upon the surface that bounds the two media. The path of the light in the denser medium forms a smaller angle with the perpendicular to the bounding surface than does its path in… … Fig. 9. sine of the angle of incidence, and the line C D is the sine of the angle of refraction. The proportion between these lines, when the media concerned are air and water, is approximately as 4 to 3, or for air and glass, as 3 to 2. These proportions expressed as fractions are the " refrac-…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
![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-378-261.webp)
