A JAPANNED AND LACQUERED BRASS FORTIN-TYPE MERCURY STICK 'MOUNTAIN' BAROMETER Pasterelli and Rapkin, London, early 20th century The instrument with slender cylindrical case pierced with a vertical slot to reveal the tube incorporating sliding Vernier collar reading against a scale calibrated in barometric inches ranging from 20 up to 32.5 inches to the right hand margin opposing millibar scale to the left, the shaft with Vernier adjustment disc to right and engraved signature PASTORELLI & RAPKIN, 46 HATTON GARDEN, LONDON to centre over applied mercury tube Fahrenheit and Centigrade scale thermometer with canted scale and enclosed bulb to front, the base with cylindrical glass chamber enclosing mercury and incorporating inverted ivory level pointer to interior clamped between horizontal plates over cylindrical cistern and adjustment screw to base, mounted via a brass ring to top and base collar-bracket with triple securing screws onto a rectangular moulded mahogany panel with curved top and base. The instrument 102cm (40ins) high; the wall panel 105cm (45.5ins) high, 9cm (3.5ins) wide. Provenance: The Selwyn Demmy Collection. The firm of Pastorelli and Rapkin are recorded in Banfield, Edwin BAROMETER MAKERS AND RETAILERS 1660-1900 as being established in 1872 as a prolific maker of barometers of all types of barometers who worked from 61 Hatton Garden and 7 Great Warner Street, London in 1872 and then 46 Hatton Garden from 1873. The firm was incorporated as a Limited Company in 1901 and was still trading (in various guises) until 1988. The current lot is made to the principles laid down by Nicholas Fortin (1750-1831) and incorporates a glazed cistern so that the level can be calibrated via the adjustment screw to the base against an inverted conical ivory cone in the cistern in order to obtain consistency in the readings. This particular type of barometer provides an accurate reading hence was generally adopted for laboratory use throughout the 19th and early 20th centuries. The scale of the present lot is unusual in that it ranges from 20 up to 32.5 inches rather than the usual circa 26.5 to 32 inches. The facility of being able to read particularly low pressures is indicative of an instrument intended for use at high altitudes hence instruments that incorporate this feature are sometimes referred to as 'mountain barometers'. Condition Report: Instrument is filled with mercury and provides a good reading with no apparent airlocks and the Vernier slide is operational. The brass case is in sound condition but has patchy strong discolouration and wear to the original lacquered finishes. The back panel is in good condition. Condition Report Disclaimer