Stick mounted Fortin-type standard barometer with thermometer also attached to the tube by brass and steel fittings. At foot of the glass tube a black painted steel casing protects the mercury reservoir (now empty). The whole instrument is mounted on a mahogany blackboard with special wooden supports to further protect the reservoir.
Detailed dimensions:
Overall height: 115 cm
Glass tube length: 88 cm
Thermometer: 18 cm
Scale: 28 cm
Inscriptions:
[Top] No. 2222
[label on backboard] NEGRETTI and ZAMBRA / Inst. Makers / to Her Majesty / London
[metal label around tube:] 2222 / STANDARD / CONDITION / TEMPERATURE 0˚C / {etc.}
Formerly used at the Royal Observatory Greenwich (Meteorological Department) and Royal Observatory Edinburgh before returning to the National Maritime Museum in 1984.
For more details about this type of instrument, see ‘A Treatise on Meteorological Instruments, Explanatory of Their Scientific Principles, Method of Construction, and Practical Utility’, Henry Negretti and Joseph Zambra, Chapter 1, section 4, pp.4-5 (1864).