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[[circled]][[No 12 & 9 mixtures?]] [[/circled]] The news in the dark room 3 scales one of 100 inches another 150 inches and a third 200 inches These had been divided by young Been under the direction of the Mr Lederle. [[end page]] [[start page]] [[in pencil]] 31 [[image - pencil drawing of a long rectangular vessel with a filling hole, marked: Lamp for testing lard oil -]] With a long photometric scale the indications of the position of equably of the light is not as precise as with a shorter one but then the spaces through which the [[direcs?]] moved is proportionally greater. When a thin greased diaphragm is used to observe quality of light on the two sides or