Max-Min thermometer shows the highest and lowest temperature
Wet & Dry thermometer is used out door to measure humidity

Max-min thermometer C+F

 

Max-Min thermometer shows the highest and lowest temperature outdoor.

 

Operating instruction of wet and dry thermometer: Fill the reservoir at the bottom of the wet bulb thermometer with clean, clear water, Then place the cloth attached to the wet bulb thermometer into the reservoir. Allow enough time for the cloth to be completely wet, before reading the wet Temperature. When using the instrument, first take the reading of the dry thermometer, then verify The wet thermometer reading. Subtract the wet bulb reading from that of the Dry bulb. Find the intersection between the dry bulb temperature (oC) And the difference in temperature ( oC)For example, the temperature shown on the dry bulb thermometer is 30oC, And 25oC on the wet bulb thermometer. The difference is 5oC. Using 5oC as the vertical coordinate ( oC), and 30oC as the horizontal coordinate, the intersection point is at '64'
This means that the air humidity is R. H. 64%