… Hydrometers and similar floating instruments, thermometers, pyrometers, barometers, hygrometers and psychrometers, recording or not, and any combination of these instruments. …
Explanatory notes
… 90.25 ‑ Hydrometers and similar floating instruments, thermometers, pyrometers, barometers, hygrometers and … etc.). Nicholson’s hydrometer is used for solids. The heading does not cover : (a) Instruments which determine … thermometers and pyrometers based on the principle that the heating of the junction of two different electric conductors …