It is true, that complex colours other than those in the same wave length, may be developed by blending two colours from different parts of the spectrum, but the ray proportions of colours so produced, are necessarily more complex than those developed by specific absorption; the first being a method of synthesis towards complexity, and the second a method of analysis towards simplicity, and although two colours so produced may be similar in name, red for instance, they must differ in character. This view may tend to reconcile some of the theoretical differences between Scientists and Artists. THE ULTRA VIOLET DIVISION. The complete range of daylight colours not being fully comprised in a continuous spectrum, may be considered as a cycle of radiant energies, sensitive to the vision as colour, which can be represented as a circle as in Plate VII. The outer and broken circle represents a bent spectrum, the unoccupied division corresponding in position with that of the red and violet mixtures in the complete cycle. This arrangement does not alter the relative positions of the Fraunhoper lines A, B, C, D, E, F, G and H in reference to either scale, but, it theoretically breaks that sequence of the successive wave lengths in the Red Violet which holds good in the other five divisions from A to H. [Illustration: PLATE VII _To face page 40._] [_Lovibond, Colour Theories._ ] In order to theoretically avoid this juxtaposition of wave length contrast, it is only necessary to imagine that the violet energy beyond H in the ultra violet, is overlapped by the infra red energy of a succeeding spectrum, filling this section with a series of overlapping binaries analogous in wave length sequence to that of the other sections. A RESIDUAL RED RAY. Apart from the colours of everyday life there is, in sunlight and most direct artificial lights, an additional red energy which differs materially from the red energy in diffused daylight. It was first noticed whilst establishing the colour equivalence of the tintometrical light unit, by developing a red sensation which disturbed constancy of reading under certain conditions of light. So far as the writer knows, this energy has never been investigated as separate from the other spectrum red. The following observations must be considered as tentative only. SOME PROPERTIES. It does not obey the laws of absorption which govern the red of diffused daylight. When the six transparent pigmentary colours are illuminated by direct sunlight, and viewed through a sufficient number of Neutral Tint units, the colours all disappear, all appearing red alike, with only differences in luminosity. The spectrum position of this red energy is in the A. B. region, and further interception by Neutral Tint whilst narrowing the band, intensifies the colour, until obstructed by the large number of intercepting glass surfaces.