360 THE POPULAR SCIENCE MONTHLY. 



And, in his life of Pericles, he says that " green is best suited to the 

 eye by its beauty and agreeableness, and at the same time it refreshes 

 and strengthens the sight." From an old anonymous volume entitled 

 " The Gentleman and Lady instructed," published in London in 1759, 

 I extract the following : " Some authors argue for a providence, from 

 the earth being covered with green rather than with any other color, 

 as being such a right mixture of light and shade that it comforts and 

 strengthens instead of weakening or grieving the eye, and they ex- 

 plain it in this manner : All colors that are more luminous than green 

 overpower and dissipate the animal spirits which are employed in the 

 sight ; whereas those that are more obscure do not sufficiently exer- 

 cise the animal spirits ; but the rays which produce in us the idea of 

 green fall upon the eye in such a due proportion that they give the 

 animal spirits their proper play, and, by keeping up the struggle in a 

 just balance, excite a very pleasing and agreeable sensation. But," 

 says the author, " be the cause what it will, we know that its effect is 

 certain." Richerand, the celebrated French physiologist, says, in his 

 chapter on " Sensations " : " Green is the softest of colors, the most per- 

 manently grateful ; that which least fatigues the eyes, and on which 

 they will the longest and most willingly repose. Accordingly, Nature 

 has been profuse of green in the coloring of all plants, and she has, in 

 some sort, dyed of this color the greater part of the surface of the 

 globe." Dr. Thomas Dick, in his work " On the Improvement of So- 

 ciety by the Diffusion of Knowledge," remarks, page 206, section 6 : 

 " As the eye is constructed of the most delicate substances, and is one 

 of the most admirable pieces of mechanism connected with our frame, 

 so the Creator has arranged the world in such a manner as to afford it 

 the most varied and delightful gratification. By means of the solar 

 light, which is exactly adapted to the structure of this organ, thou- 

 sands of objects of diversified beauty and sublimity are presented to 

 the view. It opens before us the mountains, the vales, the woods, the 

 lawns, the brooks and rivers, the fertile plains and flowery fields, 

 adorned with every hue, the expanse of ocean, and the glories of the 

 firmament ; and, as the eye would be dazzled were a deep red color 

 or a brilliant white to be spread over the face of Nature, the Divine 

 Goodness has clothed the heavens with blue, and the earth with green 

 — the two colors which are the least fatiguing and the most pleasing 

 to the organs of sight ; and, at the same time, one of these colors is 

 diversified by a thousand delicate shades, which produce a delightful 

 variety on the landscape of the world." 



Dr. Phene, in a paper read recently by him before a scientific so- 

 ciety in Edinburgh, advised the planting of trees in cities ; among the 

 beneficial results of which he mentions " the relief to the optic nerve 

 through the eye resting on objects of a green color, and that, as the 

 power of sight is strengthened and sustained by green glasses, a similar 

 advantage would be gained by the presence of the green foliage in the 



