EARLY 19TH C HYDROSTATICAL GLASS BUBBLE SET BY J. HERON
Add-1301. English, 1st quarter 19th century, with a trade label in the lid signed "Hydrostatic Balls For Proving Spirits, Proved and Sold by J. HERON, Watchmaker, and Jeweller, No. 1, William Street, Greenock." A set of 12 'spirit beads' or 'philosophical bubbles', each with a short stalk, so weighted that they neither rise nor sink when in the liquid that exactly matches their particular calibration, thus indicating the degrees of proof spirit. All of the beads are in fine condition; the original turned wood case is in good overall condition, except for a 1 1/2" missing piece in the edge of the top. See page 95 in Turner's "Nineteenth-Century Scientific Instruments" for a similar set.
