COLOUR-BLINDNESS OR DALTONISM.

Otago Witness, Issue 1874, 21 October 1887, Page 32

COLOUR-BLINDNESS OR DALTONISM.

Daltonism is the name that was first given to what is now generally called colour-blind-ness. It arose from the circumstance 1 hat John Dnltou, Ihe great chemist who discovered the atomic theory, was the first to call public attention to the defect. He was born in 1776, but did not discover that there was anything the matter with his vision until 1792. Before this he was very much perplexed about colours, and in his own mind had come to the conclusion that everybody was in a state of confusion on the subject. At last, some one made an observation in his presence upon a geranium flower ; this led him to compare his impressions with the impressions of some friends, and the conclusion was 'thus forced upon him that his vision was peculiar. To him red appeared as a shade simply, pink as sky-blue, a florid complexion he compared to diluted black ink or dusky blue, and a laurel leaf he thought a good match for a stick of red sealing-wax. Before Dalton, a case in Maryport, Cumberland, had excited a little attention. The subject was a shoemaker named Harris. When four years old he found a child's stocking in the street, and inquiring for the owner, he noticed that the people called it a red stocking. Though he was a mere child, j^et this seemed to him to conflict with former expressions he had heard as to colour. He was a bit of a thinker this shoemaker, and after arriving at years of discretion, he came to the conclusion that there was something wrongr. A gentleman in the neighbourhood, hearing of the case, wrote about it to Priestley, who laid the facts before the Royal Society. Harris could not distinguish cherries on a tree except by their shape. He had a brother who confounded yellow with green. Among the mistakes said to have been committed by colour-blind people are recorded the following : — A naval officer purchased red breeches to match his blue uniform ; a tailor repaired a black garment with crimson cloth ; a painter coloured trees red; the sky pink, and the human cheeks blue; a clerk wrote a letter half in black and half in red ink. In Homer's time, [ according to Mr Gladstone, the colour-sense of the human race was defective ; might it not have been that Homer himself was colour-blind? Tradition says that he was blind altogether, and it is hardly fair to infer from what a blind man says about colours that the colour-sense of mankind was as yet undeveloped. Another well-known case of colour-blind-ness was that of William Pole, a friend of Sir J. Herschell. Pole betrayed his defect at the age of 10, when he mistook a piece of red cloth for a green leaf. Subsequently he had a good deal to do with drawings, and in colouring them he had to be told what colours to use. He says that the beautiful rose light of sunset on the Alps, which threw his friends into rapture, seemed all a delusion to him. Dr Whewell one asked Dalton to what object he would compare his doctor's robe, which was of a brilliant scarlet ; the latter pointed to the trees, and declared that he perceived no difference between the colour of his dress and the colour of their foliage. Combe mentions an Edinburgh brassfounder who confused the colour of red sealing-wax with that of grass, and could not see any difference in colour between a piece of scarlet cloth and the hedge it was hanging on. A lady once put Prussian blue

nn her face instead of rouge; and abookhinder's apprentice was chastised by his master' for using red paper to cover books that he had been ordered to cover with green.