250 



LIGHT 



their eyes from time to time in order not to injure them; a 

 prisoner whose cell faced a whitewashed fence on which the 

 sun shone was permanently blinded by the glare. In arctic 

 regions where the sun is brilliantly reflected from snow and ice, 

 the glare is terrific, and the strain on the eyes is intense. Eski- 



FIG. 121. A well-lighted display at the left. The lamps are concealed. A poorly 

 lighted window at the right. The bright unconcealed lamps produce a glare. 



mos, the inhabitants of these regions, cover their eyes with 

 wooden strips in which there is the merest slit for the passage 

 of light to the eyes. Travelers and explorers to these regions 

 wear dark glasses or veils as a protection to the eyes. Few 

 people are subject to such intense strain as these, but unless 

 we are careful we subject the eyes to strains which in time 

 injure them permanently. Reading or sewing with the sun 

 shining on book or material, working in the twilight, working 

 in front of lights that are not softened and scattered by globes, 

 working with the light shining in our faces instead of on the 

 objects, are illustrations of common strains which should be 

 avoided. 



