Finding the Dew-point. 131 
wet-bulb and then whirl or fan the instrument, 
when the temperature will fall. Continue the ven- 
tilation until the wet-bulb thermometer ceases to fall, 
when the two thermometers should be read. Subtract 
the reading of the wet-bulb thermometer from that of 
the dry. Find this difference in the column at the 
left of the table. The dew-point will then be 
found at the intersection of the line opposite this 
difference and the column which is headed by the 
number nearest the air temperature (dry-bulb 
reading). Examples are given below: 
“Dry-bulb thermometer 
Wet-bulb thermometer 
Dry-bulb thermometer 
Wet-bulb thermometer 
DUET OTCS ieee case jose aves setieisye Seorei ats Sie aie eraneys & eesniaue nats dows Sianavouate 5° 
Dew-point from table, between 27° and 33°, about....... 30° 
“DEW-POINT TABLE. 
Difference of reading of Temperature of Air — Fahrenheit. 
dry and wet bulbs. 15°| 20°| 25°| 30°] 35°| 40°| 45°] 50°| 55°| 60°} 65°) 70° 
