The theory of ocular defects and of spectacles

Historical Significance: This is a translation of Scheffler's Die Theorie der Augenfehler und der Brille (Wien, 1868) includes seventy-three printed pages of material which did not appear in the German original. This matter, giving practical instructions on the examination of the eye and the selection of lenses, was specifically requested from the author by Carter for inclusion in his English translation. Carter felt that this book successfully approached problems left unresolved in Donders's work on defects of accommodation and refraction. Scheffler (1820-1903) was a German engineer, mathematician and a physicist who wrote on mathematics as well as subjects as diverse as hydrostatics and hydraulics, steam boiler explosions, deaths and insurance as well as physiologial optics and laws of spatial seeing.