A fine scarce lacquered brass five glass mahogany cased combination barograph and barometer with thermometer c1920
Antique barograph having 3½” x 3⅝” drum with seven day duration, platform escapement, captive key, hinged paper clip, top nut keeper and lid. The barometer section raised on four turned pillars, blued screws and pivots, polished cross shafts, eight cell pressure sensor, polished recording arm.
Fusee driven barometer with 4⅜” open centre dial, the upper part marked “Stormy, Rain, Change, Fair, Very Dry” and calibrated in inches of mercury with a range from 28–31″, divided to 10ths and 50ths, the lower portion with curved thermometer calibrated in degrees Fahrenheit and Centigrade with ranges 0–140° and -10–60° respectively, blued steel pointer.
The long lacquered brass chassis with adjustment knob and arrestor bar. Mahogany case with base mounted ink station, original bottle and dipper, frieze drawer. The lid with five bevelled glasses.
Condition: This barograph has been the subject of a complete rebuild, conservation, and calibration under laboratory conditions, and pressure tested to full scale deflection. Bespoke Vavasseur replacement recording arm and nib.
Comments: We have yet to acquire a barograph that did not require a total overhaul – these are very delicate instruments. The very nature of a barograph – essentially a mechanical amplifier – demands that all aspects are set to optimum in order to obtain good results.
At first glance most of these instruments appear to be very similar, and the differences that might set one instrument as very good and another as poor are subtle. This is a first quality piece, and working on these fine instruments is a privilege and a pleasure. As a first quality instrument, it has an eight cell pressure sensor, the rare benefit of a curved thermometer set to the barometer dial, and is housed in a fine quality case. As the performance chart demonstrates, its accuracy is absolutely spot on.
Though unsigned, it would be hard to find a better example of these increasingly difficult to find instruments.
Dimensions: 14¾” wide x 8¾” high x 9″ deep
Stock No: BG0970