… Hydrometers and similar floating instruments, thermometers, pyrometers, barometers, hygrometers and psychrometers, recording or not, …
Explanatory notes
… AND SIMILAR FLOATING INSTRUMENTS These instruments are used for determining, generally by direct reading on a … stem, the specific gravity of solids or liquids, or some arbitrary value related to specific gravity (e.g., strength … for instance). These consist of an oscillating lever, one arm of which moves before a dial, the other connecting with …