This is a Fortin barometer.

It was part of a collection that we acquired from gentleman who worked in the maritime industry across the globe for over 30 years. 

Manufactured by Asco in Masulipatam, India (an old English and French port) it is made from brass. It is fitted inside a case and would have been hung vertically on the wall with the case opened to take readings. 

We have been told that this type of barometer was issued to vessels that were nominated to take metrological readings and is most likely circa 1920/30.

An amazing piece, and very rare.

Measures approx: Box-121cm x 18cm x 16cm Gauge-1m long