HYDROLOGY OF NEW YORK 



147 



then forced underneath, cutting the frame and contents free, the 

 box and contents inverted, and a bottom of copper, dishing slightly 

 to a common center, where a pipe was inserted and securely sol- 

 dered, and to which a perforated guard was attached, was strongly 

 fastened into position by bending the copper sides over the edge 

 of this bottom piece and securely soldering. 



These three boxes were then carried from the point of filling 

 to the drain-gage lawn, where they were placed carefully in posi- 

 tion, their surfaces level with the surrounding ground and the 

 pipe which passed from their bottom carried into a subterranean 

 alcove built below them, and upon the arch of which the boxes 

 rested, with the intervention of about six inches of soil. These 

 alcoves branched from a pit carefully arched and to which admit- 

 tance is obtained by steps. A bottle kept under each drain gage 

 and to which the pipe leads enables us to collect all the water 

 which drains through, and a graduated measure enables us to 

 measure this water in thousandths of an inch, thus making a 

 ready comparison with the rainfall, a record of which is kept by 

 one of Green's eight-inch gages located alongside. 



In order to estimate the drainage from different kinds of soil, 

 these gages have different classes of surfaces. On the surface of 

 No. 1 is a heavy sod ; of No. 2 the surface is bare and undisturbed ; 

 while of No. 3 the surface is kept pulverized during the open sea- 

 son by frequent stirring with a trowel. 



An edging of hard brass, one inch high, extends around the top 

 of the frames, accurately defining the area. Hence, all the rain- 

 fall over the area is compelled to enter the soil and by measuring 

 the amount percolating, we can account for the balance which 

 evaporates. Having the three gages we can calculate the amount 

 of water evaporated from growing sod, from a bare surface and 

 from a stirred surface, respectively. The difference between the 

 precipitation and drainage from such gages is taken to represent 

 the evaporation from the ground. 



In order to show the meteorological conditions existing at 

 Geneva, table No. 32, Precipitation at Geneva Agricultural Ex- 

 periment Station for the Water Years 1883-1889, Inclusive, is 

 given. This table, however, while apparently a table of precipi- 

 tation, does not give a complete record of precipitation in the 

 form of snow and is somewhat deficient as to quantity during the 

 winter months. Nevertheless there is a tendency to very low 



