8 1 THE POPULAR SCIENCE MONTHLY, 



it also is yellow under the former illumination ; the white paper and 

 yellow object, therefore, appear of the same hue ; but knowing the 

 paper to be white, and through an error of judgment accepting the 

 prevailing illumination as white, the yellow object appears of this 

 color. In view of these facts, it would seem that deductions drawn 

 from the composition of white light are in favor of making it one of 

 the colors. As supporting this view of the matter, might be men- 

 tioned Langley's investigations which have shown that the true color 

 of sunlight, before some of its constituents have been filtered out by 

 the atmosphere, is decidedly blue ; and that, according to Briicke, 

 ordinary daylight is slightly reddish in tint. It might be claimed as 

 a reason for excluding white from the color series that it has no repre- 

 sentative in the solar spectrum, but there is equal reason for exclud- 

 ing purple, unquestionably a color, which has no type in any part of 

 the spectrum, being produced only by a mixture of rays from the red 

 and violet portions of the spectrum. And it has been proved by sev- 

 eral observers that all of the spectrum colors when increased in inten- 

 sity tend toward white, and if made dazzling actually become white. 

 Accepting this fact in a liberal sense, it is plain that white has a rep- 

 resentative in every part of the spectrum ; and this tendency toward 

 white with increasing illumination being also a property of black, we 

 have a direct argument for the inclusion of the latter with the colors. 

 In conclusion, it may be urged that the adoption of white and 

 black into the chromatic scale is desirable for the sake of simplicity 

 and uniformity in the nomenclature of this subject. 



+ 



THE PHILOSOPHY OF DIET. 



By a Layman. 



IN the years to come it will be debated whether the great minds of 

 the later Victorian era were most concerned with their souls or 

 with their stomachs. Politics we may put by ; they are always with 

 us ; but politics apart, between these two interests, the spiritual and 

 the peptical, the question of precedence must surely lie. What other 

 claimant can there be? Not literature, thrust away into corners, or 

 tricked out in a newspaper like some May-day mummer ; not art, di- 

 vorced, in Carlyle's phrase, from sense and the reality of things ; not 

 music, crushed Tarpeia-wise under foreign gewgaws, or brayed in a 

 chemist's mortar ; not the drama, leveled to a tawdry platform for 

 the individual's vanity. Not these, nor any one of these things ; but 

 the soul and the stomach, irreligion and indigestion, doubt and dys- 

 pepsia call them what you will these are the cardinal notes of our 

 great inquiring age. 



The former I will not touch. Sir Henry Thompson, indeed, asserts 



