1896. NOTES AND COMMENTS. 87 



This preliminary test showed that only about forty per cent, were 

 possessed of what is regarded as normal vision. Of the remaining 

 4,900 odd, between two and three thousand were examined by 

 Mr. Carter or by Mv. Belcher Hickman, who assisted him in the 

 investigation. The examination of the whole number was impossible 

 for many reasons, of which the chief was that their professional occu- 

 pations made it impossible for the two gentlemen to conduct their 

 investigations except in the afternoons. Moreover, a considerable 

 number of parents objected, and holidays and the termination of 

 school career interfered with the examination of many cases. It is 

 believed, however, that quite a sufficiently large number of cases was 

 studied to lead to valuable conclusions. 



One of the most striking results is that there appears to be no 

 special reason for attributing any increase in short sight to the 

 influence of school-work and school accommodation. Many of the 

 worst cases occurred in particularly well-lighted schools, and among 

 children who were so young that the influence of school life could 

 have had little time to operate. Moreover, recent optical work has 

 made it possible to distinguish between simple myopia, which is 

 more than likely to be an inherited structural peculiarity, and the 

 progressive myopia which results from undue straining of the eyes. 

 Cases of the latter kind were very rare, and bore no relation whatever 

 to school life and school accommodation. This report will be a source 

 of considerable comfort to many anxious school managers. 



Process-Engraving in Colours. 



In our note on the new photography and natural science (vol. 

 viii., p. 375), we threw out a suggestion as to the application of photo- 

 graphy in colours to the production of half-tone blocks for printing 

 purposes. A greater advance than we even dreamt of has, however, 

 it appears from the Photogvam, been made by Mr. James W. 

 McDonough, of Chicago. His discoveries consist, first, of photo- 

 graphing colours, and, secondly, of the application to purposes of 

 printing. The photographic process is a simple adaptation of ordinary 

 photography. A glass screen, ruled with lines from 300 to 600 to the 

 inch, like chat employed in the usual manufacture of half-tone blocks, 

 has its lines coloured with aniline dyes, red, green and blue succes- 

 sively, the colour being everywhere of the same thickness. This is 

 placed in the camera, immediately in front of an orthochromatic dry 

 plate, on which a black and white negative is obtained with lines 

 corresponding to the screen. From this negative the positive is made 

 in the ordinary manner on glass or paper. If the transparent positive 

 be placed in front of a screen like that used in the camera, so that 

 the lines exactly register, the photogram will appear in natural 

 colours ; or if the paper on which the print is made be ruled exactly 

 like the screen with red, green, and blue lines, which it may be men- 



