One piece silvered and engraved dial incorporating barometer and weekly barograph. The aneroid barometer with standard meteorological terms, calibrations in inches of mercury with a range from 27″ – 31″ and divided to 1/20th”, the inner dial with basic weather prognostications. Blued steel pointer and gilt brass index. Early pattern movement driven from a 2” single capsule tensioned on a coil spring and contained within a drum form lacquered brass case, the movement struck “5”.
The manually adjusted barograph comprising seven threaded and extending pins operated from dedicated knobs at the foot of the register, so marked with weekdays on horizontal axis and pressure calibrated in inches Hg on the vertical axis. All set in a gilt brass surround and recessed within a silvered reflector.
All contained within an ebonised oak case, classically mid-Victorian transport handle to top, the whole raised on a moulded plinth with inverted conical bright-plated cast brass feet. The verso with opening door on a catch affording access to the barometer and adjustment port.
Condition: The subject of a near complete re-build and re-calibration, tested and calibrated under laboratory conditions. The barometer performing well within reasonable parameters with good sensitivity and progression, see performance chart below.
The barometer dial and barograph crisp and clean, some minor marks to barometer dial centre. Some losses to dial wax. Retaining virtually all its original silvered finish. The rack and pinion pressure indicators move with correct resistance. The timber case structurally sound, some wear to sharp edges, small or minor indentations, the door hinges sound and locking mechanism is positive. One adjuster and screw, extreme right, an old replacement.
Overall, this is a good, clean and very original instrument in excellent working order.
Comments: A very important catalogue on the design and evolution of barometric recording devices so vital in the early days of weather forecasting. We know of six of these instruments only, and have examined three – this is one of the most extraordinarily interesting meteorological instruments encountered. Clearly made in very small numbers – this one is marked “5” and the other two we have seen marked “4” and “8” – and almost certainly as a party to the manufacture of drum barograph recorders which at this time were just appearing. The question has to be asked, why were there not more of them? This instrument would clearly have been a cheaper alternative to a drum barograph recorder and, with a little conjecture, it might be that they were more a marketing exercise aimed at parochial opticians where the clientele might be more easily persuaded as to the instrument’s merits. In any event, they clearly required some discipline by the owner to faithfully record the day’s pressure. The idea of the instrument is very sound, the practical operation of it, less than convenient – the drum barograph recorder a much more practical proposition.
Two versions of this instrument are known. Some are undressed oak – this, the black and gold version, in our opinion has the greater aesthetic value.
Probably on the same level as the Atmos Barometer (though the Atmos was essentially just a barometer), this instrument stands as representatively most important as a creation born of the infancy of forecasting. They may both, though, have something of the synergy of the drum barograph recorder.
Without doubt a most important collector’s piece. Not unique but extremely rare.
Dimensions: 6” wide x 9” high x 3½” deep
Stock No: BG1955