1893.] NATURAL SCIENCES OF PHILADELPHIA. 349 



THE RADIUS OF CURVATURES OF THE CORNEA. 

 BY HENRY C. CHAPMAN, M. D. AND ALBERT P. BRUBAKER, M. D. 



The classification of the sciences has at various times engaged the 

 attention of philosophers. Whether or not the thoughts of students 

 of biology have ever been directed to the merits of the classifications, 

 among others, of Bacon, 1 Comte, 2 Spencer, 3 the most superficial 

 thinker must have been impressed by the fact that whatever be the 

 logical order of the study of the sciences, the progress of any one 

 branch of science has depended largely upon the simultaneous 

 advance made in some closely or even remotely allied branch. 



The influence exerted by the progress of physics upon that of 

 astronomy and biology through the invention of the telescope and 

 microscope respectively, the stimulus to mathematical research exci- 

 ted by astronomical discoveries, the influence of physics upon chem- 

 istry, may be cited as familiar examples. As a special instance 

 of the manner in which the different branches of science are related 

 to each other, it may be mentioned that the method of measuring 

 the radius of curvature of the cornea by means of the ophthalmo- 

 meter is essentially the same as that made use of by astronomers in 

 determining the angle subtended by the apparent diameter of a 

 celestial body by means of the heliometer. 



Though not perhaps generally known, there was submitted as long 

 ago as 1743 to the Royal Society a communication by Savery, giv- 

 ing an account of his invention of " A new way of measuring the 

 difference between the apparent diameter of the sun .... with a micro- 

 meter placed in a telescope invented for that purpose." Savery's 

 paper was not, however, published at that time, it having been 

 apparently entirely forgotten by Bradley to whom it was referred. 

 Ten years afterward, during the year 1753, Short having learned 

 that Bouguer had given an account in 1748 to the Academy of 

 Sciences of Paris 4 of his invention of the heliometer, and wishing to 

 secure for his countryman the credit of the invention, called the 

 attention of the Royal Society, in whose Transactions 5 it finally 

 appeared, to the long neglected communication of Savery. 



1 De Augmentis Scientiarum. 



2 Cours de Philosophic Positive. 



3 Genesis of Science Essays, 1868. 



4 Historie de L' Academie Royale des Sciences a Paiis, MDCCLII, pp. 87, Mem- 

 oires p. 11. 



5 Philosophical Transactions, Vol. XLVIII, p. Ili5. 



