On Light in some of its Relations to Disease, 167 



be found of more universal application and more successful 

 in its workings than any which has been advanced for the 

 mitigation of this class of affections. 



Many hundreds of persons suffer the strain upon the eye 

 and upon the nervous system, as the result of these visual 

 troubles, who are entirely unconscious of any defect of 

 sight. 



A robust-appearing German friend, who had adopted 

 glasses for the correction of refractive errors on account 

 of a nervous difficulty, when asked to describe the effect 

 of his glasses upon him, replied : " When one who has a 

 tight coat that he has worn so long he don't know it is tight, 

 because he is used to it, gets another coat which is big 

 enough, then he knows how he feels so much better. That 

 is the way with my glasses. I did not know how bad I 

 feel before, until I got my glasses and felt so much better." 



How often do we see children of our schools, frequently 

 the brightest and most ambitious of their class, struggling 

 with irritable nerves, at a disadvantage in their studies, 

 laying the seeds of future trouble, and often, as the time 

 comes for selecting a pursuit in life, forced to abandon a 

 chosen course of studies, because the confinement at such 

 work is too great a strain upon them ! I look forward to 

 the time when these children who, from this single pecu- 

 liarity, are placed at so serious a disadvantage in the 

 struggle for life, shall find the relief that science is ready 

 to afford them, and which would remove the weight that 

 would otherwise prove a serious hindrance in their course. 



We may compare the heart of a man to the main-spring 

 of a watch, while the delicate nerves which control the ac- 

 commodation of the eye may be compared to the fine hair- 

 spring of the time-keeper. It matters little how often we 

 wind the watch, and thus supply tension to the main-spring, 

 if the delicate hair-spring is not well fixed in its place — if 

 it is a little too long or a little too short — our watch is 



