A textbook on mechanical and electrical engineering (1902)
International Correspondence Schools · Scranton : International Textbook Co. · leaf 246
per and tracing are smoothedout so as to lie perfectly flat upon the glass, the cover A isreplaced, and the brass spring clips B, B are sprung underthe plates D, so that the back cannot fall out. While allthis is being done, the paper should be kept from the lightas much as possible. The frame is… … Fig. 16clear or cloudy—and the time of the year, the print mustbe exposed from 3 to 15 minutes. The tray, or sink, alreadymentioned, shoukl be filled to a depth of about I inches withclear water (rain water if possible). The print having beenexposed the proper length of time, the frame is carried…
