Barometers Realm

The barometer’s dial, stamped from silver-plated brass, displays a barometric scale in London inches of mercury, ranging from 28 to 32 inches, with divisions as precise as 1/20 of an inch. The scale markings are executed in a bold, "Goliath-style" design. Notably, there is no textual weather indication, while the top of the dial bears the engraved title "Forecasting Aneroid." The long, ultra-thin indicator needle, gliding gracefully along the dial, is made of blued steel and features a crescent moon as its tailpiece.

At the heart of the barometer lies a nickel silver capsule with a diameter of 5 cm. The mechanism is temperature-compensated for enhanced accuracy.

This barometer, crafted as part of a custom-ordered, limited-edition set, includes the patented Negretti & Zambra weather forecaster. The forecaster, made of brass with a crackled finish on its reverse side, complements the barometer. An identical Negretti & Zambra forecaster made of celluloid is also known to exist. This explains the absence of standard textual weather indications on the dial. The title engraved at the top of the dial — "Forecasting Aneroid" — further confirms that the barometer was part of a unified set with the weather predictor. Both instruments — the barometer and the weather forecaster — were housed together in a wooden case wrapped in pigskin leather.

Whiteside-Cook’s Patent

The Whiteside-Cook’s Patent, registered under number 14424, represents an innovation in aneroid barometer design, engineered for precise atmospheric pressure measurement at sea level regardless of the current altitude. This was achieved through a specialized mechanism allowing the user to set the current altitude, after which the instrument automatically adjusted the pressure reading to the sea-level equivalent.

In operation, the crown is turned counterclockwise, enabling the case back, to which the movement is attached, to rotate. A scale from 0 to 3000 feet is engraved around the case's circumference, and the altitude is set by aligning the engraved index point located on the case back. The crown is then turned clockwise to lock the new value in place.

The Whiteside-Cook’s Patent, registered in the late 19th century (circa 1870), is closely associated with Negretti & Zambra, although it was originally designed and patented by the engineer whose name it bears. The patent essentially described a correction system for barometric pressure readings, enabling adjustments to sea level for greater accuracy. Negretti & Zambra, as one of Britain’s leading meteorological instrument manufacturers, extensively utilized this patent in their barometers, making the technology widely recognized.

The same technology was also employed in barometers by Short & Mason, which featured instructions such as: “For sea level reading, rotate this plate until the arrow on the case points to the altitude of your locality.” This technology was particularly notable in their fisherman’s barometers, produced under the Taylor brand.