Unpublished photograph, experimental apparatus by William R Jack A photograph of the instrument designed by Jack for producing 'tracings of a larger series of lines upon the plate than the microscopic slide could contain' in his analysis of voluntary muscular movements. The instrument consists of 'a hollow brass cylinder made as light as possible, and carrying a roll of smoked paper. The axle had at one end a grooved wheel, which was connected with a similar wheel attached to the clockwork by an endless band.This furnished the rotary movement.' Subject: Scientific apparatus and instruments 1895