Estimated Date: 1875
Name: Sphygmograph, Richardsons
Description: 5× 3“x 2” leatherette case contains device similar to Dudgeons but with 2” rod which extends and has an adjustable weight to adjust pressure rather than screw spring. The body of the instrument is 2” long, there is a 2” sq. clockwork mechanism to turn the smoked paper on a rod drive. No manufacturers marks on the instrument. Case has handwritten letter GAT, very similar to an English model. French?
Reference 1: 122