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An antique brass machine for measuring wind speed.
The text in the label in the box reads (as much as I can read of it) as follows:
International Inventions Exhibition Awarded Silver Medal
Correction for Air-Meter No. 20
Add 30 per minute to the observed reading of the Air-Meter.
Note—Each measurement[?] is regulated so as to reduce the co[missing] to a constant quantity per minute, which must be[missing] in the example given.