Marine Barometer by Negretti & Zambra No 1139 c1905 – SOLD
Negretti & Zambra marine barometer with 5″ engraved, silvered and lacquered dial, calibrated from 25-31 inches of mercury. The upper portion annotated “Stormy,” “Rain,” “Change,” “Fair” and “Very Dry,” and “Compensated,” the lower signed by the maker “Negretti & Zambra, London” with serial no. “1139.” Blued-steel pointer, gilt brass telltale and bevelled glass. Conventional pattern 2½” capsule-driven movement with modifications for marine use, including bronze hairspring, anti-corrosion coating applied to steel parts, heavy drum-formed case with separate heavy bezel ring, the fixing lugs attached to the back plate with screws, and the movement retained with flathead screws and spacers.
This is an interesting and very attractive instrument constructed with notable attention to detail and clearly of high quality. A fine instrument with several refinements based upon the preceding 40 years of production, and, as developed, better suited to its intended marine environment than those models produced before. These innovations include: a bronze hairspring instead of the more usual steel; full anti-corrosion treatment of the movement; and the means of retaining the movement in the case is designed to prevent vibration from machinery and engines causing the movement to separate from the back plate. In this instance, the movement is bolted mechanically to the back plate from which it is held away by spacers, again to reduce the effects of vibration. In almost all other cases, save for those instruments constructed in aluminium, the movement is attached to the case by machine screws into ferrules soldered on to the back plate. It is the failure of the solder due to vibration and salt that this design addresses. The substantial external bulkhead mounting lugs are again screwed to the case rather than soldered. In addition, each lug has a step that engages with the circumference of the case to prevent it from rotating. Finally, the dial is lacquered, again to mitigate the effects of salt corrosion. is noteworthy that this is a low serial number, suggesting a separate unique series in production. There is no means of knowing how many instruments in this form were produced, however, this is the first example we have examined or seen.
A very collectable and most attractive instrument with a highly sensitive movement and step-less progression. Fully serviced and very crisp overall, it remains original in all respects.
Dimensions: 6¼” diameter (exc. lugs) x 2½” deep
Stock No: BA0374
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