324 



LIGHTING OF INTERIORS. 



largely upon the distance of the lamps from the reflecting cefling^. 

 The results are illustrated in Fig. 14. We get the best results 

 when the distance of the centre of the lamp is 75 cms. from the 

 ceiling. The ordinates of the curve represent average values. 

 Fourteen candle metres gave results entirely satisfactory. Shadows 

 almost disappeared, and the result was highly pleasing. The 

 lamps used were four Tungsten one watt' lamps of 65 mean 

 hemispherical candle power, so that with inverted lamps, fixed 

 at the best distance from the ceiling— a distance depending on 

 the type of shade and the reflector employed- — we require for a 

 mean illumination of 15 candle metres in a room with very light 



^5 

 yellow walls and a white ceiling, approximately 4X — = 4-3 British 



24 

 candles per square metre floor space. For white walls this reduces 

 to approximately four candles for the same illumination. If the 

 reflection takes place not from the ceiling but from special reflec- 

 tors, in places where the ceiling is painted a dark colour, where 

 the walls are also of a dark tint, more light is required to ensure 

 the same comfort. One would, however, hardly employ inverted 

 lamps in rooms with walls painted in dark colours. The writer 

 intends to carry out further experiments in connection with in- 

 verted lighting. At present it may be mentioned that better 



(CO 



150 



zoo 



250 



o 50 



CENTIMETRES 



DISTANCE OF LAMP FROn CEIUNG (iNDniECT ILLUMlNAriON}. 



FUj. 14. 

 results are obtained if the reflector below the lamps is perfectly 

 opaque, than with a shade which allows part of the light to pass 

 through. The difference between two shades of identical shape, 

 one opaque and the other semi-transparent, amounted to about 

 14 per cent. 



In conclusion, I should like to point out again that the results 

 given in this paper must be considered as only approximately 

 correct. In lighting it is impossible to lay down rules holding in 

 all cases, and one must rely on experience. The experiments, 

 however, should be of some use, when the planning of new build- 

 ings takes place. In the writer's opinion inverted light is used 

 far too little, because it is considered too expensive. In reality 



