Beschreibung:

Ω A rare George III inlaid mahogany mercury wheel barometer with unusual indication Joshua Springer, Bristol, circa 1795 With triple line-edged rounded top inset with a hygrometer scale engraved DRY/MOIST and signed Springer, Bristol over conforming strung baluster outline upright with large glazed rectangular Fahrenheit scale mercury thermometer flanked by foliate oval lozenge marquetry motifs, the 8.5 inch circular register further signed J. Springer, Bristol to centre over central spindle applied with ivory pulley assembly flanked by text Fair if Rise opposing Foul if Fall, the lower section beneath the spindle with vertical scale calibrated in barometric inches 28-31 and annotated with usual observations, the circumference with concentric scale divided for hundredths of a barometric inch annotated for every tenth, the rounded base with marquetry fan rosette, (unrestored, lacking hygrometer centre and glass, tube, bezel, hand and cursor weight), 97cm (38.25ins) high. Joshua Springer is recorded in Goodison, Nicholas English BAROMETERS 1680-1860 as succeeding the London scientific instrument maker John Wright (who had trained under Benjamin Cole and settled in Bristol in 1756) in 1759. Springer initially worked from Hadleys Quadrant, St. Stephen’s Lane, Bristol, before moving to 2 Clare Street in 1775 where he remained until 1808. Goodison notes several angle barometers by Springer in addition to a very small group of wheel barometers made with the same design of dial as the current lot. The highly unusual register plate of the current instrument is designed to allow the vertical barometric scale beneath the centre spindle to be read via a small brass cursor weight suspended from a line wound around the ivory pulley. This is in-turn, driven by a second pulley on the other end of the spindle connected in the usual manner (via a line and glass float) to the open-end of the mercury syphon tube. The diameter of both pulleys have been carefully tuned to ensure that the spindle revolves once for every barometric inch covered, thus allowing the hand to provide a reading to two decimal points for each inch covered by the cursor weight. Another example by Springer with an almost identical dial to the current lot is illustrated by Goodison on pages 246-47 (plates 168 and 169). Cites Regulations Please note that this lot (lots marked with the symbol Ω in the printed catalogue) may be subject to CITES regulations when exported from the EU. The CITES regulations may be found at www.defra.gov.uk/ahvla-en/imports-exports/cites