The subject of the physical and physiologic characteristics of the eye have been elucidated since the time of Euler in 1753. The most prodigious work was that of Helmholtz, who laid the ground work for the present author's thesis on the use of the cobalt lamp for the objective study of the refraction of the eye. Helmholtz's work appeared in 1866 with rather crude instruments. Since then, Snellen, Donders and finally Gullstrand have perfected this method.
The author reviews the work of previous authorities and then illustrates by beautiful color plates the results of many years of work with the new cobalt lamp.
Certainly, he has brought to modern perfection this method of retinoscopy. The detailed mathematical formula and concise theoretic conclusions leave little to be desired.
The literature is covered in full with a long bibliography. The index is short but adequate. Too much emphasis cannot be given to