A Japanned And Lacquered Brass Mountain Fortin Barometer By Pasterelli

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