Light and Vision

Abstract

AT a meeting of the Illuminating Engineering Society following the annual general meeting on May 11, Sir John Parsons gave an address on “Light and Vision”. In his opening remarks Sir John recalled his presence at the inaugural dinner of the Society in 1909, and the recognition of the founder of the Society, Mr. Leon Gaster, that its aims were not limited to physical problems, but involved physiological, psychological and aesthetic factors. At that time there was little guidance on lighting matters from the medical side, but engineers had themselves little data, and instruments for measuring illumination were primitive and cumbersome. The first paper read to the Society on glare in 1910 was given by himself, and the Society has since been preoccupied with this and similar problems involving vision. Sir John then discussed the relation between illumination and visual acuity, directing attention to the valuable work of Dr. Lythgoe and others and the development of the Illuminating Engineering Society's Code. Research has established the great importance of background and adequate contrast. The work of Dr. Stiles and others on glare (for which we have no actual physiological test), the effects of specular reflection from polished material and the inconvenience and occasional danger of harsh shadows-most difficult, however, to define with precision-were dealt with. Turning to the colour of light Sir John expressed the view that there is no evidence that artificial sources furnishing so-called 'white light' cause any harmful effects. The injurious effects of ultra-violet light in everyday life have been grossly exaggerated and the craze for 'daylight' lamps has been unwarranted.