2 Color Standards and Nomenclature. 
number of colors they all fail to supply a ready or 
convenient means of identifying and designating the 
colors—the principal utility of a work of this kind. It is 
in the latter respect that the present work is believed to 
meet, more nearly than any other at least, this essential 
requirement, and in this consists whatever originality 
may be claimed for it. 
The “key” to the classification or arrangement here¬ 
with presented is, of course, the solar spectrum, with its 
six fundamental colors and intermediate hues, augmented 
by the series of hues connecting violet with red, which 
the spectrum fails to show. If, with the red-violets and 
violet-reds thus added to the spectrum hues, the band 
forming this scale be joined end to end a circle is formed 
in which there is continuously a gradual change of hue, 
step by step, from red through orange-red and red-orange 
to orange ; orange through yellow-orange and orange- 
yellow to yellow; yellow through green-yellow and yellow- 
green to green; green through blue-green and green-blue 
to blue; blue through violet-blue and blue-violet to violet; 
and violet through red-violet and violet-red to red—the 
starting-point—with intermediate connecting hues. In 
the solar spectrum, both prismatic and grating, but 
especially the former, the spaces between the adjoining 
distinct colors are very unequal; therefore for the present 
purpose an ideal scale must be constructed, so that an 
approximately equal number of equally distinct connect¬ 
ing hues shall be shown. Distinctions of hue appreciable 
to the normal eye are so very numerous* that the 
criterion of convenience or practicability must determine 
the number of segments into which the ideal chromatic 
scale or circle may be divided in order to best serve the 
purpose in view. Careful experiment seems to have 
^According to Aubert more than 1000 hues are distinguishable in the spectrum, 
though among them all the hues betweeen violet and red are wanting. 
