A good aneroid pocket barometer altimeter and thermometer stepped dial compendium c1885
Pocket barometer having 1¾” French silvered and die struck stepped dial, outer rotating altitude ring calibrated in feet with a range from 0 – 8,000ft and divided down to 100ft, the inner barometric scale calibrated in inches of mercury with a range from 23” – 31” divided down to 1/20th”. The lower part with curved inset thermometer, the register calibrated in degrees Fahrenheit with a range from 20° to 110°. Blued steel pointer, bevelled glass.
The 1st quality ‘bat wing’ bridge movement, unsigned but probably by Negretti & Zambra, driven from a single nickel silver capsule tensioned on a coil spring, the decorated chassis struck “G”, the verso struck “17.” All contained within a semi barrel form case with ribbed embellishment. The verso with calibration port, suspension post and bow.
Presented in its correct burgundy leather over timber, green silk and velvet lined case, snap closure on a button release.
Condition: The subject of a full service, conservation, and calibration under laboratory conditions. The movement working well across the standard barometric range 28” – 31” Hg with an expected loss of accuracy at the lower pressures, see performance chart from dynamic test.
The dial clean and with good definition, the thermometer thread unbroken and reading approximately 0.5 of a degree high at 70°F. The lacquered brass case retaining a good proportion of original finish with evidence of some wear, minor marks, etc. The leather transport case structurally sound and with good colour, the fabric interior clean and sound though the lid silk shows some fading and marks.
Comments: Quite an unusual instrument from the point of view of dial construction, the altitude ring of substantially deeper form than previously observed and not part of the dial, though the impression is of a stepped dial.
Visually attractive, a very good example of this type of instrument in easily collectable condition.
Dimensions: 2¼" wide x 2⅝" long x 1⅛" deep
Stock No: PB2370