The color chips of metameric pair to judge a color temperature of light source are manufactured for trial, of which spectral distribution curve is shown in Fig. 1.
The metameric pair causes various color differences according to the variation in color temperature of light falling on it.
The chromatic loci of the metameric pair for each of temperatures are represented along the nearest plankian locus on a chromaticity diagram such as Fig. 2.
In the process of producing these color chips, if a light source, of which color temperature was known, used for judgement, it would become feasible to distinguish their color differences by human eyesight.
In making the above chips, we resorted to such a method that the NBS unit of color difference of metameric pair was computed for a desired color temperature and those with the least NBS unit were made eligible.
It should be very convenient to have these metameric pairs arranged in the riget order of their color temperatures, because in this way color temperature of any given light source can be determined by comparing its light color with that of those metameric pairs.

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Twenty eight men were tested with two lanterns at a distance of two hundred and fifty meters in the day time, evening and night; according to method of “color-naming”. Of these, 10 were color normal and 18 color deficient according to Ishihara test and anomaloscope, Of the latter, 11 were classified deuterano and 7 protano.These were also tested with 3 pseudo-isochromatic tests of color vision (Ishihara, Oguchi and Okuma tests), anomalscope and Farnsworth-Munsell 100 Hue tests.
The results obtained on the lantern are as follows:1) The difference between color normal and deficient lies in the results that color deficient is apt to make different kinds of responses. 2) Incorrect responses were made to the yellow light more often, and white, red and green less often. 3) Protano confused more often one colored light with other colored lights than deuterano does. 4) The correlational technique were used to study the responses on lantern. That is, the pseudo-isochromatic tests correlate better with each other than they do with lantern. 5) The intercorrelation between the results on the lantern and Fransworth-Munsell 100 Hue test is not high, but the correlation coefficiency, to some extent, yields quantitative estimates of the amount of color defect.
The results of these studies show that the test on lantern is worthy for criterion of color deficiency.

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