Whilst we constantly read claims of virtually any Kriegsmarine item being referred to as being from a U Boat, this extremely rare Barometer by Lufft is indeed the type only used on U Boats.
Calibrated in Millibars from 800 to 1500 (far higher than any normal atmospheric pressure) it was used to reflect pressure within the hull of the submarine and especially on those boats using a Schnorkel with the diesel engines running.
The pressure would drop when the float on the schnorkel was hit by a wave and thus shut the air way for the engines. They would then be drawing air from within the boat reducing its pressure to the detriment of the crew’s ears and eyes etc.
This is a quote from the interrogation report for U-490:
“He constantly watched a barometer and when the pressure dropped from 1020 millibars (normal) to 850 millibars, one Diesel was shut off. If the pressure dropped to 750 millibars, both engines were stopped.”
Contained in its original storage box and complete with the original 1944 dated Test Certificate, both of which carry the serial number as the instrument itself, the Barometer measures 130mm in diameter and is in very good functioning with some dust visible on the inside of the glass.
The black dial shows the Lufft name, below which is “Only for Technical use” (I assume rather than for meteorological use), the Kriegsmarine eagle over M and the serial number, 4694/OBS. On the backplate a screw cover gives access to an adjustment point where the indicator can be adjusted to a known value.
The storage case is in excellent condition and as rare to find as the Barometer itself, the lid with the same wording as the dial along with “Precision-Barometer”.
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