Wohlgemuth, Adolf, b. 1868 · Cambridge, University Press · leaf 49
ields can be seen with alternating black and white horizontal lines, like the surrounding front board. The "fields" consist of endless bands 15 cm. wide of painted paper or other material sewn or pasted on tracing-linen, to prevent stretching and to give consistency. Each band passes over a pair of… … Fig. 3. Fig. 2. Fig. 2. "Apparatus of moving fields." Front view. Fig. 3. "Apparatus of moving fields." Back view. by their weight. The upper drums nearly touch each other, and each is held in position by a pair of prongs that slide along and can be fixed to a second horizontal iron rod running…
