THE paper on “Underground Lighting in Mines” read to the South Wales Branch of the Association of Mining Engineers by R. H. Campin and published in the Mining Electrical Engineer for February is a helpful and useful paper. Special stress is laid on the importance of miners' hand lamps. Mr. Campin points out that most of the hand lamps now in use are virtually of the same type as those developed before 1915. There are approximately 750 thousand hand-lamps in use in Great Britain. About fifty per cent of them are flame safety lamps. The popularity of the flame type is probably due to the fact that it automatically indicates the presence of inflammable gas. Most of the electric lamps in use are of a somewhat antiquated type giving only one candle power and supplied by a two volt battery in a celluloid case. The number of lamps supplied by alkaline batteries is about four per cent. There is no doubt that in many cases improved lighting would considerably increase the output as well as diminish the total number of accidents per annum on which compensation has at present to be paid. The author mentions the case of a German mine where the effect of doubling the illumination was to increase the output per man-shift by about 30 per cent. Doubling the light increased the cost of the lighting from a halfpenny to a penny per ton of coal raised. Medical investigations have shown that nystagmus ris practically a light deficiency disease. The collieries have to spend £440,000 annually in compensation to sufferers from it. If lights of not less than four candle power were used, the number of cases would be greatly diminished* The author thinks, that the illumination of many of our collieries could be tripled or even quadrupled without increasing operating charges. Flood-lighting at localised spots is recommended.