The drum barograph mechanism overall of grained and lacquered brass. The fully enclosed drum marked “7D” (seven day movement), captive winding key and regulator, securing nut, sprung side-mounted chart retainer with fixing clip, cover, the whole raised upon a chassis-mounted turned-steel spindle with sun gear to base. The barometer driven by twin 2¾” horizontally-mounted capsules tensioned by a nickel plated ‘C’ spring, heavy machined brass top lever with compensation adjustment wheel to side, bi-metallic temperature compensating connecting lever. Twin pivot shafts raised on barrel-form columns with grained white metal recorder arm and screw tension adjustment, blued-steel top screws and pivots. The full chassis annotated “Mark II” and “Reg No 554620,” fitted with arrestor bar and lever, mercurial thermometer set on a silvered brass back plate with scales in degrees Celsius and Fahrenheit, ink bottle holder with cobalt blue ink bottle, corked dipper.
The end-hinged polished mahogany case set on bracket feet with twin swinging catches, decorative gilt brass carrying handle, frieze chart drawer below and maker’s plate.
This drum barograph is unusual in that the aneroid barometer closely follows designs employed in pocket, marine and bulkhead types, the capsules held in tension by a ‘C’ spring and acting through a heavy top lever. Well-constructed, the instrument shows good sensitivity and function. It has been disassembled, cleaned and checked, and remains in original condition in all respects. The ink bottle, though of the same period, is not original to the item.
Dimensions: 13″ wide x 8″ high x 6″ deep
Stock No: BG0301
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