Apart from the pleasure its sensations give to all properly constituted persons, the study of colour has an intellectual value in common with other branches of science. It strengthens the judgment by constantly requiring thought and precision in definition, it also develops the faculty of colour perception even to the point of curing some forms of colour blindness. In addition to this, it forms a necessary part of the instruction in all schools in which drawing is properly taught by methods which demand from the pupils faithful representations of the appearances of actual objects in colour as they are seen. In the past the systematic study of colour has been more or less neglected from two principal causes: first, the want of a comprehensive scheme of colour nomenclature capable of describing all colours in terms precise enough for general understanding and record; and, second, the absence of any reliable means of reproducing any specific colour if lost or faded. Both these conditions may now be secured by the use of the standardized coloured glasses supplied with the Colour Educator, and this work is intended to bring the subject before teachers in such a way as to make each point perfectly easy of demonstration to a class in a systematic manner. To-day the value and importance of a keen perception of colour and of an apparatus furnishing definite colour standards, though perhaps not much appreciated by the general public, are widely recognized in the industrial and scientific world; and it is evident that in these days of keen commercial competition between nations we cannot afford to neglect any means which will enable us to maintain present industries and to develop new ones. =General Remarks.=--It is not advisable to introduce colour theories to pupils before they know the names of the different colours, but, as the glasses used in the apparatus are graded for colour-depth according to a set of scales now generally accepted as of standard value, a short description of the derivation of the colour names will be of service when the pupils are sufficiently advanced. The names of the six spectrum colours, Red, Orange, Yellow, Green, Blue, and Violet, are accepted by common consent as describing the principal hues into which a beam of white light can be resolved by a diffraction grating or by prismatic refraction. They are also the colours distinguishable in objects of everyday life, and the following Educational Method is based on the fact that they can be separated at will from ordinary daylight. Therefore the first educational step is to associate these six colour rays with their respective names, the pupils being made to understand that there are many degrees of depth in each colour.