Mechanics' magazine and register of inventions and improvements . without by being behind the curious con-tractile window curtain, the iris, through thecentral opening of which, or pupil, the lightenters. Immediately behind the pupil is sus-pended by attachments among the ciliary pro-cesses, the crystalline lens, a double convexmost transparent body of considerable hard-ness, which so influences the light passingthrough it from external objects as to formmost perfect images of these objects in theway already described, on the back wall of theeye, over which the optic nerve, then called thereti
Mechanics' magazine and register of inventions and improvements . without by being behind the curious con-tractile window curtain, the iris, through thecentral opening of which, or pupil, the lightenters. Immediately behind the pupil is sus-pended by attachments among the ciliary pro-cesses, the crystalline lens, a double convexmost transparent body of considerable hard-ness, which so influences the light passingthrough it from external objects as to formmost perfect images of these objects in theway already described, on the back wall of theeye, over which the optic nerve, then called theretina, is spread as a second lining. The eyeis maintained in its globular condition by a wa-tery liquid, which distends its external cover- ings, and which in the compartment before thelens, or the anterior chamber of the eye, beingperfectly limpid, is called the aqutous humor,and in the remainder or larger posterior chamrber, being inclosed in a transparent spongystructure, so as to acquire somewhat of theappearance of melted glass, is called the The annexed figure represents an eye ofthe common dimensions, supposed to be cutthrough the middle downwards. C is the out-er or sclerotic coat, known popularly, wheremost exposed in front, as the white of the is the transparent cornea joined to the edgeof the round opening of the sclerotic : it ismore bulging than the sclerotic, or forms aportion of a smaller sphere than the generaleye-bali, so that while it may be truly called abow window, it, or rather the convex surface ofits contained water, is also a powerful lens foracting on the pencils of entering hght. At B,and similarly all around the edge of the cornea,is attached the window curtain or iris, shownhere edgeways, immersed in the aqueous hu-mor, and hanging inwards from above andbelow towards its central opening or pupil,through which the rays of light are passing tothe lens. The iris has in its structure two setsof fibres, the circular and the radiating,
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Keywords: ., bookcentury1800, booksubjectindustrialart, booksubjecttechnology
