PLATE 6 
A. —Shallow, blackened evaporation tank mounted on automatic balance. The 
reservoir is shown above in the back. The tank has an area of 6,540 sq. cm., and the 
water is maintained at a depth of approximately 1 cm. 
B. —Deep evaporation tank as used at Akron, Colo. This tank is 6 feet in diameter 
and 2 feet in depth, and is buried in the ground to within 4 inches of the top. The 
water level is kept at 4 ± 1 inches from the top of the tank. The well of the recording 
gauge (not shown in the figure) is connected with the tank by a buried pipe. The 
well for the micrometer gauge may be seen (covered) on the right side of the tank. 
