Walnut Wall Barometer by Callaghan No 5224 c.1878

A rare walnut cased aneroid wall barometer and thermometer for Robert Bottomley by William Callaghan No 5224 c.1878. Aneroid barometer having 7½" vitreous glass painted dial, the barometric scale calibrated in inches of mercury with a range from 27" – 31" divided down to 1/50th, standard meteorological terms, the centre marked with retailer’s details, "Bottomley, 11 Billiter St, London." Blued steel pointer, Callaghan gilt index with remote setting knob. Bevelled glass and oxidised brass bezel. The movement, serially numbered "5224," driven from twin 2½" nickel alloy capsules tensioned on a C spring,  the primary lever with inverted compensation strip, the bridge marked with date "6/6/78." The thermometer of standard design mounted to a vitreous glass register calibrated in Reaumur and Fahrenheit with corresponding ranges -10° to 40°  and 10° to 130°, also marked “Freezing Point,” box surround with single glass. All presented in a burr walnut frame with carved walnut floral friezes. Condition: The subject of a full service, conservation, and calibration under laboratory conditions. The movement working exceptionally well with good progression and accuracy better than 1/10th" across the scale, see performance chart from dynamic test. The barometer dial clean with some slight losses and evidence of minor restoration to applied numbering. The thermometer accurate within 1½° at 67°, the register with hairline crack. The timber case structurally sound with signs of ageing, some minor impressions and light abrasions. Comments: William Callaghan instruments are superior to most other makers and substantially better than the mainstream instruments of this type. Twin capsule aneroid movements are extremely unusual, fitted to an instrument of this type suggesting exacting standards required by the customer. Callaghan made many instruments as white labels - known for his quality of materials and craftmanship, only the most exclusive of retailers stocked and sold his instruments. This is not only a very attractive and clearly high quality piece, it is demonstrably practical. With lighter timber tones the simple lines fit well in many settings, lending both style and undeniable interest.