Brass cased mining aneroid pocket barometer altimeter, c.1885, priced £425 from Vavasseur Antiques.

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The dial lacks a serial number and the scale suggests it might have been made for use in the very deepest mines of the time.

The dial is signed for James J Hicks of Hatton Garden who featured portable mining aneroid barometers in his Illustrated Catalogue of Meteorological and Scientific Instruments, c.1870. However, it is known that Hicks bought in the vast majority of the instruments he supplied, with this one almost certainly made by Francis Barker, a very respected manufacturer who was predominantly a supplier of white label instruments to the trade.

The pocket barometer, which is named verso for the owner KHH Allen, is priced at £425 from Totnes dealer Vavasseur Antiques.