GREY RAINBOWS

Otago Witness, Issue 3619, 24 July 1923, Page 41

GREY RAINBOWS

SIX COLOURS VISIBLE TO MOST PEOPLE. Although we speak of sunlight as being white, it really consists of every known hue blended together in certain proportions. This is revealed to us wherever the sari shines through rain clouds in such a way that its white beams are decomposed into the glorious spectacle of the rainbow ,states “H. C. V.’” in the Daily Mail). This natural spectrum, or rainbow, forms the basis of ail our ideas of colour. The beautiful hues which so brighten our lives are due to the power which our surroundings have of selecting certain color rays from the sunbeams and radiating them out to us. Thus the reds radiate red and the greens radiate green sunbeams, and so on, as the case may be. Hence, it comes about that a dress which looks beautiful in daylight may not look so well at night-, as the colour rays contained in artificial light are not identical with those of the sun. Light comes to us in waves, and the colour depends on the rapidity of the vibrations producing it. The red rays are the least and the violet the most rapid: between these two are all the colours we are able to recognise. No human eye has ever been able to see more than seven distinct colours in the rainbow, and very few people are able to distinguish more than six. Our ability to appreciate colours depends on the acuteness of the colour centre in the brain. When the centre is very badly developed one colour only is seen, and the whole rainbow appears as a dull grey. This condition is only very rarely met with, apart from disease. Those in whom the centre is slightly more developed can distinguish the two colours which differ most in wave length—red and violet, with or without a neutral in between.

As development goes on. the next colour to be appreciated is green, lying midway between red anil violet. The next point of greatest difference in wave length lies between the red and the green—namely, yellow. People belonging to this four-unit group can see only red, yellow, green, and violet. The next stage in development is reached in five-unit people, who can see blue appearing between the green and ihe violet. Similarly, orange is seen be- j tween tlie red and vellow in six-unit people, who form the majority of mankind at the present day, and are therefore looked upon as normal. Some few individuals, numbering onlyone in several thousands, have their colourcentre so well developed that they can detect a seventh colour, indigo, between violet and blue.