The exemplar in the museum is a Regnault hypsometer consisting of four superimposed brass tubes. The first two are both 17.5 cm in length with diameters of 8.8 cm and 6.4 cm respectively; they are joined together. The second, which acts as the water boiler, penetrates by about half its length into the first, which is also the base of the instrument. The other two tubes, which serve as draught, are both 11.5 cm in length and have diameters of 4.3 and 2.6 cm respectively. The third one fits telescopically into the second and the fourth into the third.
A large opening in the side of the base tube allows the lighting and snuffing of a cylindrical alcohol burner which, inserted from the base, adheres perfectly to the walls of the latter and is fixed there by a bayonet mount.
A small side tube near the top of the instrument acts as a steam valve.
The thermometer with a large bulb, graduated in half degrees from 92 to 105 degrees Celsius, is attached by means of a cork stopper to the upper base of the instrument and penetrates into it by about 20 cm.
Since the distance between two lines on the scale is almost 2 mm, it is possible to obtain a reading to a quarter of a degree Celsius. With this thermometer, the scale of which goes from 0 to 92 degrees Celsius, the hypsometer can measure altitudes up to 2500 metres above sea level.
The overall height of the instrument with the thermometer in place is 80 cm.


Bibliografia:
Privat Deschanel (1869), p. 339
Turner(1983), p. 245


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