The Optical Magic Lantern Journal (March 1898)

48 The Optical Magic Lantern Journal and Photographic Enlarger. In 1890 Mr. F. E. H.Varley invented another means of obtaining an intermittent feed for the film. By referring to Fig. IX. we see that the film is wound upon the drums 15, 17, the latter of which is the winding-on drum, and it passes over the guide rollers 34, 35, 36, and 87. The | drums are actuated by springs in opposite directions, and are also in gear with one another, so that the tension of the spring of the drum serves to wind the spring in the other drum serving to keep taut the sensitive film. By an oscillating lever 46 terminating in a lever 45 the film is intermittently fed in lengths equal to the parts exposed to the rollers 34, 35. In withdrawing a length of film from the drum 15 the movement of the lever winds the spring of the drum, and as this winds the spring of the first drum the second drum winds on the film. Detents 61 and 67 are used to prevent a reverse movement of the film. The shutter, which consists of a perforated disc 88, Ki K TF Fig. X. revolving in front of a fixed perforated piece, is actuated by cams on the shaft 76. (No. 4704 of 1890.) Fig. X. illustrates another method invented some years later by Friese Green. The film 2 is wound from the spool d tothe spool k by means of a handle mounted upon the driving shaft B in gear with the spindle of the roller k. By means of the spring arms o and small roller s actuated by eccentricsr, a definite length is pulled off the roller d: the arm o being guided in its motion by the guide rollers h j, and the spring clamp u being drawn off k. The slack is taken up gradually, and the film held