Early type of Richardson sphygmograph, in case, c.1883, English Early type of Richardson sphygmograph circa 1883
Richardson sphygmograph (modified Dudgeon) c.1906, in case Richardson sphygmograph (modified Dudgeon) c.1906 1901-1910
Dudgeon sphygmograph by Mayer and Meltzer, in case, English Dudgeon sphygmograph by Mayer and Meltzer
Dudgeon sphygmograph by Krohne and Sesemann, in case, English Dudgeon sphygmograph by Krohne and Sesemann 1870-1900
Part of a Sphygmograph(?) gilt brass and nickel plated brass with rubber drum, French, 1880-1920 Part of a Sphygmograph(?) gilt brass and nickel pl 1880-1920