It is desirable that a record of the children’s own painting should be preserved, with a view to discriminating between errors arising from Colour Blindness and Colour Ignorance, the former perpetuating itself, and the latter naturally remedying itself. For this purpose painting books containing sets of diagrams corresponding to the figures in the foregoing pamphlet can be supplied.
Appendix II
THE POSSIBILITIES OF A STANDARD LIGHT AND COLOUR UNIT.[5]
The past attempts to standardize light and colour are mainly limited to those radiant energies which excite light and colour sensations under diffused daylight conditions, because in direct sunlight, and in most artificial lights, there are other colour energies, which, unless sufficiently modified by diffusion, disturb the colour readings. There are also latent colour energies, which only become distinguishable by special means. They do not, however, appear to influence diffused daylight colour work.
The definition of a normal vision is one which agrees with a majority of others. This definition has proved satisfactory up to the present, as the normals are many and the colour blind few.
Light Intensities.—There are two methods of determining light intensities by means of a graded scale of light absorbents.
First. By total absorption of the light, when the intensity is directly represented by the unit value of the absorbents required. This method is applicable for low lights, internal surfaces, such as a desk, etc., where a standard light is not available for comparison.
Second. By the reduction of a standard light by absorption until it equals the light of the object. In this case the standard must be originally brighter than the object.