Soil hydrometers: Used to analyse the soil by the departments of farming, forest, water conservancy, architecture, etc.
土壤计：供农林、水利、建筑等部门对土壤分析之用。
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Hydrometers and similar floating instruments, thermometers and pyrometers, barometers, hygrometers and psychrometers, recording or not, and any combination of these instruments.