Light and lighting . A view of the Lecture Theatre of the Institution of Civil Engineers, London. Theillumination is derived mainly from the white frieze lighted by concealed lights,and there aie also mercury vapour lamps above the glass in the central a knowledge of the dimensions of the room and the area and surface-brightness of the illuminated frieze it is possible to estimate the illuminationprovided at the level of the seats and Council table (Mr. A. P. Trotter). B 2 232 THE ILLUMINATING ENGINEER (may) The point at which the illumination Is tobe found is 20 ft. below the cove.
Light and lighting . A view of the Lecture Theatre of the Institution of Civil Engineers, London. Theillumination is derived mainly from the white frieze lighted by concealed lights,and there aie also mercury vapour lamps above the glass in the central a knowledge of the dimensions of the room and the area and surface-brightness of the illuminated frieze it is possible to estimate the illuminationprovided at the level of the seats and Council table (Mr. A. P. Trotter). B 2 232 THE ILLUMINATING ENGINEER (may) The point at which the illumination Is tobe found is 20 ft. below the cove. From0 draw an arc OH of 20 ft. radius, anddraw OH at right-angles to OD. JoinDH, then DH, which scales 324 ft., isthe slant height from the point D onthe cove to point H 20 ft. below it, and. 20/32-4 is the cosine of the angle ofincidence. From the square ol theslant height and the cosine we obtain•240 foot-candle for the illuminationfrom AB. and similarly 108 from BOPom times the sum of these is 1-392,which h only 2 per cent, different fromthe former result. (Probably a fluke.) The radius of the equivalent circlemay be found and is aboul 25 ft. Therelation is the same as that of themagnetic force due to a rectangular coiland to a circular coil. Mr. QaSTBB said he was sun all presenl appreciated the great amount of work Mr. Clinton had put into his paperand the air with which his calculationshad been made. In these calculations Mr. Clinton hadpreferred to go righl hack to firstprinciples, and to work out the illumina-tion from a knowledge of the polar curves ami the positions in which thesources were placed. This was desirablein order to make the calculations ofgeneral application to all systems oflighting. Manufacturers of lamps and tittitiLs. many of whom a few y
Size: 1930px × 1295px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthori, bookcentury1900, bookdecade1900, bookpublisherlondon
