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 with a fair degree of accuracy. The Weather Bureau issues evaporimeters when they are deemed a necessary part of the equipment of a station. Field evaporimeters of different patterns, each for a specific use, are used at various Weather Bureau stations.

A bottle with straight sides may be inverted in a pan and used as an evaporimeter in an emergency. If the area of the section of the bottle be determined, an approximate rate of evaporation may be found. It is better to have the mouth of the bottle rest on circular pieces of blotting paper, several thicknesses being used. The flow of water through the blotting paper will be kept fairly steady by the admission of bubbles of air. It is hardly necessary to add that values obtained thus are only approximates.