Miniature mahogany cased portable barograph by Richard Freres, Paris, Ser No. 87506, early 20th Century.
These beautifully made small instruments were used both domestically for display and instustrially in laboratories and offices.
Use the 2.75mm key for winding the drum mechanism, the longer 2.25mm key is for adjusting the pen setting from underneath the base.
Fully serviced and tested
Supplied with ink and a year's supply of inches Hg charts, also operating instructions Mm Hg and mbar charts are also avaliable if preffered.