Nov., 1913 211 
A MNEMONIC DEVICE FOR COLOR-WORKERS 
Based on a consideration of Ridgway’s “Color Standards and Nomenclature” 
By WILLIAM LEON DAWSON 
W E FIAVE ALL caught ourselves making “pictures”, geometrical designs 
or graphs, out of mental concepts. Thought relations of all sorts tend 
to arrange themselves automatically into spatial groups. Thus, the days 
of the week to our minds are segments of a closed circle, or steps of a ladder, or 
links in a chain, as the case may be. If an eighth day were added to the week by 
statutory decree we should chop open our mental circle, change the curve and 
insert the new segment, or we should add another rung to our mental image of 
a ladder, or add an eighth link to our chain. But of all mental graphs I venture 
to say that our color schemes have been least perfectly organized, least logical, 
least related. Following the analogy of the chart we have sometimes pictured 
color groups in two dimensions, but the charts themselves remained dissociated, 
unorganized, arbitrary. What may be the extent of Ridgway’s indebtedness to 
other color theorists I do not know — he hints at such indebtedness in his “pro- 
logue” — hut so far as zoological color-workers are concerned it remained for the 
orderly mind of Robert Ridgway to so present color relations that we may con- 
ceive them in three dimensions, to fix it indeed so that we must so conceive them. 
To be sure the limitations of book making still necessitate the use of dissected 
charts serially presented. But even with this handicap the sequence is so logi- 
cal that we are able to reconstruct a mental cube or visualized color-file having 
length, breadth and thickness. 
Color-file is perhaps the best name for this new piece of mental furniture. 
Let us conceive it as made up of prisms, cubes, of colored glass. To understand 
its order, therefore, let us examine its first or facing wall — thirty-seven cubes, or 
columns of cubes, wide, and nine tiers, or rows of cubes, deep. The central 
tier reading from left to right comprises the pure colors of the spectrum, red, 
orange, yellow, etc., together with carefully selected intergrades, orange-red, 
orange orange-red, red-orange, etc., — thirty-six colors to be known as hues (with 
red repeated at the extreme right to give meaning to the violet-red series). 
The bottom tier of our wall is pure black, the limit, or asymptote, of the suc- 
cessively deepening shades produced by mixing the pure color of the central 
member of each column with increasing percentages of black. The top tier of 
our wall is pure white, the limit, or asymptote, of successively lightening tints 
of the central color produced by increasing dilutions of white. In Ridgway's 
scheme three steps are made in each direction, so that we have seven colored 
tiers separating the black and the -white boundary tiers. 
So much is commonplace ; the next step is inspiration — Ridgway's. The 
third dimension of our color file is secured by progressive dilutions of neutral 
gray, additions of a uniform amount in a given wall, each block differing from 
its neighbors in the same wall in precisely the same degree in which the pure 
color blocks differ from their neighbors. It is obvious that if progressive addi- 
tions of gray differed only by one percent, we should have one hundred walls, 
bounded on the rear by a wall whose central tier -was pure neutral gray and 
whose successive tints approached the top layer of pure white, and whose suc- 
cessive shades approached the bottom layer of pure black, as in the first wall. 
As a matter of convenience only five such progressively grayed intermediate walls 
are found necessary to cover for practical purposes the whole range. 
