An exceptionally rare barograph by Negretti & Zambra. This instrument has four capsule stacks arranged as two balanced pairs and their deflections are transmitted to the main lever through flexing strips therefore avoiding hysteresis (friction errors) & loss of motion.
A large open scale, the pen travels 5” for 3” of mercury.
Set into a light oak case with beveled glass & chart
These instruments were manufactured in very limited numbers for professional use & very rarely come on the market.
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