Thus,
suppose I interpose an artificial cloud before the slit of the
spectroscope, having adjusted the two shadows, it will be seen that the
passage of steam in front of the slit does not alter the relative
intensities; but this result must be received with caution. [The lecturer
then proceeded to point out the contrast colors that the shadow of the
rod illuminated by white light assumed.]
I must now make a digression. It must not be assumed that every one has
the same sense of color, otherwise there would be no color blindness.
Part of the researches of General Festing and myself have been on the
subject of color blindness, and these I must briefly refer to. We test
all who come by making them match the luminosity of colors with white
light, as I have now shown you. And as a color blind person has only two
fundamental color perceptions instead of three, his matching of
luminosities is even more accurate than is that made by those whose eyes
are normal or nearly normal. It is curious to note how many people are
more or less deficient in color perception. Some have remarked that it is
impossible that they were color blind and would not believe it, and
sometimes we have been staggered at first with the remarkable manner in
which they recognized color to which they ultimately proved deficient in
perception.
Pages:
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124