French. c.1875-1880, in gilt brass and ivory, with aluminium plate (to which smoked paper was attached) in velvet lined fitted case, case 21.2cm [CITES]

Note: Mahomed improved on Marey’s 1857 design by adding a wheel to vary the pressure on the radial artery in increments (ounces 1-14 Troy as measured on a dial). The main concern with the Marey’s instrument was that pressure screw could not be adjusted by a measurable amount. Frederick Mahomed (1849-1884) entered Guy’s Hospital Medical School as a student in 1869 and modified Marey’s design, publishing his investigations on the year of his qualification in 1872. In place of the original screw he placed a vertical eccentric one over the centre of the spring which could be turned in graduations. This allowed the pressure needed to occlude the arterial wave to be recorded. He also replaced the side wires which attached the instrument to the arm with ivory bars. [CITES]

Note: This lot contains or is made of ivory and cannot be imported into the USA or any country within the EU.

Condition Report:The sphygmograph is in excellent condition and the clockwork mechanism functioning. Case with wear and repairs to hinge.