1893.] NATURAL SCIENCES OF PHILADELPHIA. 361 



50 50 50 



From the above resume it will be observed that, on the average in 

 young men at least, the radius of curvature of the cornea amounts 

 in the horizontal meridian to 7'797 mm., in the vertical meridian to 

 7*552 mm. 



In conclusion it should be mentioned that the importance of deter- 

 ming the radius of curvature of the cornea, depends upon the fact 

 that its value, together with that of the indices of refraction of the 

 various refractive media of the eye, constitute the experimental data 

 for determining the cardinal points of the eye. By means of the 

 latter, the paths of the rays of light passing through the media of 

 the eye, the position and size of the retinal images, etc., can be con- 

 structed or calculated, data indispensable to the comprehension of 

 vision and the practice of ophthalmology. 

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