Antique French PHNB Pocket Barometer Altimeter Silvered Dial 17 31 15000 Ft

Antique French Pocket Holosteric Compensated Barometer Altimeter by PHNB (Pertuis Hulot Naudet Bourgeois) brass case, silvered dial, blue steel pointer makers mark PHNB to dial & reverse of case (Peruis Hulot Naudet Bourgeois) barometric scale 18 to 31 altimeter scale zero to 15000 feet measures just under 7cm diameter Please see photographs.

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