. The anatomy and physiology of the human body. Containing the anatomy of the bones, muscles, and joints; and the heart and arteries . If, however, the rays be made to pass from glass into thefair, and the surface of the glass be*concave, as in fig. 4, therays will be made to have a lessdegree of convergence, so astO remove the image * fartherfrom the surface of the if the rays passing throughthe medium of glass have noconvergence, but pass in parallellines,-they will diverge as thelines A A-, fig. 4. do, when theyemerge from the concave surfaceof the glass. We see, then, the operati
. The anatomy and physiology of the human body. Containing the anatomy of the bones, muscles, and joints; and the heart and arteries . If, however, the rays be made to pass from glass into thefair, and the surface of the glass be*concave, as in fig. 4, therays will be made to have a lessdegree of convergence, so astO remove the image * fartherfrom the surface of the if the rays passing throughthe medium of glass have noconvergence, but pass in parallellines,-they will diverge as thelines A A-, fig. 4. do, when theyemerge from the concave surfaceof the glass. We see, then, the operationof a double convex glass, informing the image of a luminousbody upon a surface. If, forexample, such a glass be heldbetween a candle and a pieceof white paper, (the distancesbeing properly adjusted,) theimage of the candle will appearvery distinctly upon the opposed. 12 uF rui: £Yi. surface, but Invericd; because the rajs coming from thepoint A fig. 5, converge at c, and those from the point u at proceeding farther in this short exposition of theprinciples of optics, it will be necessary to take a very slightview of the structure of the eye. INTRODUCTORY VIEW OF THE STRUCTURE OF THE EYE. It is the first principle of the constitution of the eye, thatthe rays of light must be so concentrated as to impinge stronglyon the expanded nerve or retina in the bottom of the , as we have seen that a lens (which is a double convexglass) is necessary, so to concentrate the rays of light proceed-ing from an object, as to form a small and lively image of it(as in marginal plate, fig. 5.) so, in the same manner, an essen-tial part of the eye is the lens, Avhich brings the rays ot lightto a focus ; and that the lens may make the rays proceedingfrom an object converge into an accurate focus, so as to forma distinct image on the eye, the vitreous hum
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Keywords: ., bookcentury1800, bookidanatomyphysiolog, booksubjecthumananatomy
