. Electric railway journal . TOP OF STEEL PLATE IS CUT TO FIT UP CLOSE TO CAR FLOOR PILOT IS STURDILY CONSTRUCTED AND BRACED AGAINST SHOCK 940 Eleoteic Eailway Journal Vol. 54, No. 20 Portable Foot-Candle Meter Illumination Intensity of the Light at Any PointCan Be Read at a Glance IN ITS EXHIBITS at the recent convention of theAmerican Electric Railway Association at Atlantic Citythe General Electric Company showed a new portable foot-candle meter for general photometric use. This was de-veloped to meet the demand of electric railways for a light,compact, non-complicated instrument which woul
. Electric railway journal . TOP OF STEEL PLATE IS CUT TO FIT UP CLOSE TO CAR FLOOR PILOT IS STURDILY CONSTRUCTED AND BRACED AGAINST SHOCK 940 Eleoteic Eailway Journal Vol. 54, No. 20 Portable Foot-Candle Meter Illumination Intensity of the Light at Any PointCan Be Read at a Glance IN ITS EXHIBITS at the recent convention of theAmerican Electric Railway Association at Atlantic Citythe General Electric Company showed a new portable foot-candle meter for general photometric use. This was de-veloped to meet the demand of electric railways for a light,compact, non-complicated instrument which would measurethe illumination intensities commonly found. No specialskill is required to operate the instrument, and as it islight and compact it can be carried anywhere and read-. PORTABLE FOOT CANDLE METER ings can be taken in the same manner as with a large photo-meter and with sufficient accuracy to be of real practicalvalue. The basic principle on Mhich the foot-candle meter oper-ates is the same as that employed in the photometer. Thescreen on which the reading is taken consists of a piece ofa clear glass on which are two thicknesses of paper. Onecontains round holes fairly opaque, and the other spotswhich are highly translucent. This screen forms one sideof the light box which is so constructed that the screen isilluminated from within to a much higher intensity at theright end than at the left. The exposed side of the screen isvery nearly uniformly lighted and the round spots appearbrighter than the surrounding screen at the right end anddarker at the left, as shown in the accompanying illustra-tion. At the point where the spots change from brighterthan the background to darker, the illumination on bothsides of the screen is approximately the same. The i
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