A fine, very unusual aluminium larger size double-sided pocket compendium comprising aneroid barometer altimeter, compass, and thermometer by J.H. Steward no. 789, c1899

Pocket barometer having 2⅝” silvered and die struck dial with outer crown operated bi-directional altitude scale calibrated in feet, ascending and descending with corresponding ranges of 0 to 10,000ft and 0 to 1,000ft, each divided to 50ft. Inner barometric scale calibrated in inches of mercury with a range from 21” – 31” divided to 1/20”. The upper part with standard meteorological terms and marked “Compensated,” the lower signed by the maker “J.H. Steward, 406 Strand, London.” Fine blued steel pointer. Bevelled glass.

The first quality movement constructed with component parts of steel and frosted lacquered brass raised over a circular aluminium chassis on the essentials of the Vidie pattern, driven from a single soldered Nickel alloy 1⅝”” diameter capsule tensioned on a C spring. The bridge extension annotated “10 99” (Oct 1899) and serial no. “798.” The verso, when compass unscrewed, with calibration port, pendant, crown and bow.

The threaded detachable compass having 1¼” hand decorated mother of pearl floating Singers pattern card, displaying cardinals and intercardinal points and divided to 10°, on gem stone suspension. Transit lock. 

The thermometer of semi circular pattern with approximate diameter 2¼”, set on a circular silvered and die struck guarded register calibrated in degrees Fahrenheit and Centigrade with corresponding values 20° – 140° and -10° to 60°, each divided to 1°.

The whole contained within an aluminium cast and turned drum form case, the compass section with scalloped and ribbed circumferential decoration.

Presented in its original two tier burgundy leather over timber, green silk and velvet lined case, the lids with snap closures on button releases.

Condition: The pocket barometer the subject of a full service, conservation, and calibration under laboratory conditions, see performance chart from dynamic test. The movement function extremely good, with excellent accuracy across the range with a maximum error of .2”. 

The compendium showing little signs of use, very light wear, very minor marks and light haze to alloy surfaces (the aluminium having been re-polished). The compass working well, easily finding north, the lock arresting the card correctly. The thermometer accurate to within ½° F at 68° F.

The travel case structurally sound, both catches engaging and releasing. The leather covering with some losses, generally with fading, minor marks and minor abrasions, leather coverings to release buttons a likely period addition. The fabric interior retaining much of its chromatic depth with good colour and vibrancy, some small tears to compass lid silk and minor wear generally.

Comments: Very unusual pattern in absolutely lovely condition, and the product of a collaboration between two of the preeminent British makers of the time, J.H. Steward and Francis Barker. At the time of making aluminium was an expensive option and generally only supplied to special order. This is not a gadget instrument as many compendia were – this is a proper instrument designed for expeditions and serious exploration.