ALLA-France Wet & Dry Thermometer

Instructions:-

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.
Substract the wet bulb reading from that of the dry bulb. Find the intersection between the dry bulb temperature (?C ) and the difference in temperature (?C ).
For example, the temperature shown on the dry bulb thermometer is 30 ?C, and 25 ?C on the wet bulb thermometer. The difference is 5 ?C. Using 5 ?C as the vertical coordinate (?C ), and 30 ?C as the horizontal coordinate, the intersection point is at’ 65 ‘.This means that the air humidity is R.H. 65%.