Jason Clarke Antiques has dated this piece to the 1870s.
The dial is marked to Dollond, London with “aneroid barometer” written below.

The Dollond company was set up in Hatton Garden in 1750 by Peter Dollond with his father John joining him shortly after. John Dollond’s invention of the achromatic lens led to his award of the Copley Medal by The Royal Society in 1758 and following this success, Dollond moved to The Strand where the company was appointed optician to George III and the Duke of York in 1761.

Following the deaths of John and Peter Dollond, the name continued to be associated with royalty and went on to win a Great Exhibition Medal for “instruments for recording meteorological information on a strip of paper” (barographs). The final Dollond family member to run the company was William Dollond who sold out to a JR Chant in 1871. He continued to use the company name until was acquired by James Aitchison in 1927 whereafter it became Dollond & Aitchison. In 2009 it became part of Boots the Opticians.
Jason Clarke Antiques has dated this piece to the 1870s.
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