The practical working of the gelatine emulsion process (1880)
Abney, William de Wiveleslie, Sir, 1843-1920, author · London : Piper and Carter · leaf 23
13 THE DAKK ROOM AND ITS FITTINGS. inches long, are fitted into these tubes as shown in the diagram. It will be noticed that the gas piping … passes through the centre of these two tubes. Round the gas pipes are fitted two discs of blackened card or tin, one of which is placed two inches above the bottom hole, and the other the same distance from the top hole. These prevent light striking down the tin tube into the box. The plates, when…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
