. A compendious system of anatomy : in six parts : part I : Osteology ; II. Of the muscles, &c. ; III. Of the abdomen ; IV. Of the thorax ; V. Of the brain and nerves ; VI. Of the senses ; from the Encyclopaedia : illustrated with twelve large copperplates . equired to have such adegree of convexity, that the rays of light maybe collected at a certain point, so as to termi-nate exactly on the retina.—If the cornea istoo prominent, the rays, by diverging too soon,will be united before they reach the retina,as is the case with near-sighted people ormyopes ; and on the contrary, if it is not suf-
. A compendious system of anatomy : in six parts : part I : Osteology ; II. Of the muscles, &c. ; III. Of the abdomen ; IV. Of the thorax ; V. Of the brain and nerves ; VI. Of the senses ; from the Encyclopaedia : illustrated with twelve large copperplates . equired to have such adegree of convexity, that the rays of light maybe collected at a certain point, so as to termi-nate exactly on the retina.—If the cornea istoo prominent, the rays, by diverging too soon,will be united before they reach the retina,as is the case with near-sighted people ormyopes ; and on the contrary, if it is not suf-ficiently convex, the rays will not be perfectlyunited when they reach the back part of theeye; and this happens to long-sighted peopleor presbi, being found constantly to take placeas we approach to old age, when the eye gra-dually flattens.* These defects are to be sup-plied by means of glasses. He who has tooprominent an eye, will find his vision improv-ed by means of a concave glass; and uponthe same principles, a convex glass will befound useful to a person whose eye is natu-rally too flat. * Upon this principle, they who in their youth are near sight-ed may expect to see better as they advance in life, as their eyesgradually become more * Of the Senses and their Organs. 415 EXPLANATION OF PLATE XXX. Figure 1. Shows the Lachrymal Canals,after the Common Teguments and Boneshave been cut away. a, The lachrymal gland, b, The two punc-ta lachrymalia, from which the two lachry-mal canals proceed to c, The lachrymal , The large lachrymal duct, e, Its openinginto the nose, f, The caruncula , The eye-ball. Fig. 2. An interior View of the Coats andHumours of the Eye. a a a a, The tunica sclerotica cut in fourangles, and turned back, b b b b, The tunicachoroides adhering to the inside of the sclero-tica, and the ciliary vessels are seen passingover—c c, The retina which covers the vitre-ous humour. d d, The ciliary processes,which were continued from the
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Keywords: ., bookcentury1800, bookdecade1800, booksubjectanatomy, bookyear1805
