A very good gilt and lacquered brass aneroid pocket barometer, altimeter and thermometer compendium by Callaghan no. 4479 c1873

Pocket barometer having 1¾” silvered and engraved stepped dial, the outer bezel-set altitude scale with a range from 0 – 10,000ft divided to 100ft, split base scale calibrated +/- 1,000ft and marked Higher – Lower.

Inner altimetric scale calibrated in inches with a range from 20″ – 31″ inHg divided to 1/10″. Inset marked “Rain and “Fair,” and signed by the maker “Callaghan,” the lower part with semi-circular thermometer calibrated in degrees Fahrenheit with a range from 30° – 120°, and maker’s address “23a New Bond St, London.” Fine blued steel pointer under bevelled glass.

The standard pattern Callaghan movement based in Vidie’s original design, driven from a single 1⅛” nickel alloy capsule tensioned on a coil spring, the bridge inscribed “79,” the chassis inscribed “27/2/73,” chassis verso further struck “4470” corrected to “4479,” the case inside base inscribed “4479,” bezel inside similarly inscribed “4479.” The movement enclosed within a drum form case, engine turned bezel, pendant and bow, calibration port to verso.The chassis, inside brass case and reverse of dial all marked with initials “RT.”

Presented in its original black leather over timber, green silk and velvet lined clamshell case, the inner lid silk with gold block printed Callaghan logogram and royal warrant, snap closure on a button release.

Condition: The subject of a full service, conservation, and calibration under laboratory conditions, see performance chart from dynamic test. The barometer showing a more than acceptable level of accuracy and sensitivity across the scale with a maximum error of 0.2”, good sensitivity and progression.

The dial crisp and clean, some minor marks to centre visible only in certain incident light. The thermometer accurate to within 1° measured at 74°F. The bezel moving freely. The brass case retaining most of its original gilt and lacquered finish, minor marks and slight losses.

The leather case structurally sound, the exterior retaining most original leather and finish, some wear and ageing. The fabric interior with good depth of colour, some losses to lid silk.

Comments: This is quite an interesting instrument, not only for its triptych design but for the marks and inscriptions attached to the movement. Overall condition is very good.

A scarce and good example from this eminent London maker.