Richard Quain, (1816-1898), a physician with an office on Harley St. in London, introduced his stethometer in 1850, describing it as a new instrument for measuring the difference in the mobility of opposite sides of a patient’s chest, that was made to his specifications by Delorme, a local chronometer maker. This device is of that sort. An inscription on the dial reads “DELORME / RATHBONE PLACE / LONDON.” That on the cover reads “COXETER / XX GRAFTON ST EAST / LONDON.” James Coxeter was a surgical instrument maker who began in business in London, probably in 1836.
Ref: Richard Quain, “The Stethometer,” London Journal of Medicine 22 (1850): 923-927.