sion. The ground portions of the chains which enter the grooves formed the fastener in locking position. Fig. 2 is an inverted by the threads of the worms. The chains are firmly bottom view of the device. Fig. 3 represents a section held up against the worms by thrust-disks bearing of the blind and… … disks, which disk is not rigidly secured to the PETTINGILL’S SHUTTER-FASTENER. drum-shaft, but.is held in place by bolts passing Then the operator can focus as with an ordinarv through the slots and fastened to the adjacent disk. camera, and move the frame, H, backward or forwari blind and is…
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