Sir Humphry Davy’s Mercury Air Holder, 1800


Fronticepiece for Humphry Davy’s “Researches, Chemical and Philosophical”, published in 1800.  A mercury-seal gasometer that predates Hutchinson’s spirometer by over 40 years.  The counterweight is attached to a cam that varies the force over the range of motion of the bell.  This device was used as an air holder, not as a measuring device since the only scale for volume was a uncalibrated dial on the cam.  Found on

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