A BRASS FORTIN-TYPE LABORATORY MERCURY STICK BAROMETER A. Gallenkamp and Company Limited, London, early 20th century The instrument with slender cylindrical case with the upper section fitted with a glass sleeve enclosing silvered scale incorporating vertical slot to reveal the tube and sliding silvered Vernier slide reading against silvered scale calibrated in barometric inches to the right and millibars to the left, the upper margin inscribed No. 6728 and the lower signed A. GALLENKAMP & Co. LTD, LONDON, the shaft with Vernier adjustment disc to right over applied mercury tube FAHRENHEIT and CENTIGRADE thermometer with bulb set behind the scale, 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 walnut panel. The instrument 108cm (42.5ins) high; the back panel 103cm (44.5ins) high, 9.5cm (3.75ins) wide. Provenance: The Selwyn Demmy Collection. Adolf Gallenkamp and Company Limited are recorded in Banfield, Edwin BAROMETER MAKERS AND RETAILERS 1660-1900 as working from 2, 4 and 6 Cross Street, Finsbury, London 1880-1900 and continued trading from various addresses in Finsbury, London well into the 20th century. 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. Condition Report: Instrument is filled with mercury and provides a good reading with no apparent airlocks. The silvering to the scales is in good condition with minor discolouration/mellowing and the Vernier slide is operational. The brass case is in good condition although has probably been polished at some point (original lacquer removed) and the finish is now generally a little dull/oxidised and dirty. Condition Report Disclaimer