COLOR BLINDNESS.

Globe, Volume XXI, Issue 1777, 31 October 1879, Page 3

COLOR BLINDNESS.

A series of experiments having, by tho instructions of the Commissioner of Railways, bon made amongst the employes in the Railway Department on the subject of color blindness, have resulted in the discovery that 21 per cent, are partially color blind or unable to distinguish beyond the two primary colors black and white. The method adopted by Mr Conyers was to submit to each man seven cards, painted respectively, white, yellow, light blue, dark blue, light brown, dark green, and dark red. If each color could be named without hesitation, Che test would be considered satisfactory. The test applied on the Invercargill section was by submitting to the men plaits of Berlin wool of variegated colors, their ability to name each color without hesitation being taken as conclusive. In Christchurch 266 men have been tested, of whom thirteen are partially color blind. In the Oamaru district 230 men were tried, one of whom only was found to be color blind and he completely so. The method in this instance adopted was by colored cards, after which flags were exhibited at a distance of about ten chains. The downright necessity of these tests being applied in the interests of public safety may be appreciated when it is remembered that all the signals used on the railways by day or night are by color.