150 GARDENS AND THEIR MEANING 



construction of a simple apparatus for measuring rainfall. 

 The purpose is obviously to measure the depth of the sheet 

 of water that would lie on level ground after a rain, suppos- 

 ing that none of the water were lost by evaporation or by 

 soaking into the soil. This is done at experiment stations by 

 exposing a cylindrical vessel, or rain gauge, to the storm, and 

 measuring the depth of rain or snow that it receives. A good 

 gauge should have a circular rim and a diameter of at least 

 five or six inches. The edge should be sharp, with a vertical 

 face on the inside. This gauge should be placed in a level 

 and open space, some distance, if possible, from trees and 

 buildings (a distance at least twice their height is the rule) ; 

 then it should be fastened in place, to avoid being blown over 

 by the wind. The rim should stand a foot above the ground, 

 and should be carefully leveled. A movable funnel is generally 

 placed within the gauge, so as to protect the water that lies 

 beneath it from loss by evaporation. 



At a station the measurement of the amount of rain col- 

 lected is usually taken by pouring the water from the gauge 

 into a measuring tube of a certain smaller diameter, so that its 

 area shall be one tenth of that of the gauge. The water then 

 rises in the tube to ten times the true depth of the rainfall. 

 This magnified depth is then measured by a graduated stick, 

 the record being made to a hundredth of an inch. Record 

 should be taken, if possible, at the close of every storm and 

 always once a day, although some observers measure the 

 rainfall only at a certain hour each day, without regard to 

 the time when the rainfall ceased. The amount measured 

 should always be entered in the record book before the 

 measuring tube is emptied. Just here the hint of an expert 

 gardener may well be followed. " Buy a barometer," he says. 

 " By obeying a few simple rules you will be able to forecast 

 the weather." 



