144 NEW YORK STATE MUSEUM 



Evaporation at Rochester. Tables Nos. 30 and 31 give evapora- 

 tion at Rochester 1 for the indicated months of the years 1892-1903, 

 inclusive. The data of table No. 30 have been obtained by ob- 

 serving the changes in elevation of the water surface in a tub 

 floating on the surface of Mount Hope reservoir of the Rochester 

 waterworks, and may be taken as representing the approximate 

 evaporation from a free water surface in western New York. 



Table No. 31 gives evaporation from a water surface in an ex- 

 posed tub on land for the same years and months as are included 

 in table No. 30. 



Observations of evaporation from water surfaces for a month 

 or two have been reported from one or two other places, but so far 

 as results of any value in actual work are concerned, the forego- 

 ing include everything thus far determined in this State. 



Drain gages at Geneva. In 1882 the Agricultural Experiment 

 Station at Geneva constructed three drain gages or lysimeters for 

 the purpose of collecting and measuring drainage and evapora- 

 tion from the soil. These gages are described in the annual report 

 of the Agricultural Experiment Station for the year 1882, as 

 follows : 



Box frames a little over twenty-five inches square and three 

 deep, internal diameter, were made of oak plank, strongly ironed 

 at the corners. These boxes were lined with heavy copper fas- 

 tened to the boxes at intervals by means of heavy copper tacks, 

 and the projection of the copper at the top and bottom bent over 

 the wood and securely tacked, the area measuring after the cop- 

 per was in place 25.04 inches square, or one ten-thousandth of an 

 acre. The copper was strongly soldered at the joinings, and the 

 tack heads securely soldered into place after being slightly coun- 

 tersunk. May 29 these frames, three in. number, were fitted with' 

 a temporary cutting edge of angle iron screwed to the lower sur- 

 face, the cutting edge being parallel with the inside face of the 

 box, and the bevel toward the outside and placed over the sod. 

 By means of a heavy weight placed on top, aided by heavy mauls 

 with which blows were struck upon each of two opposite corners 

 consecutively, a ditch being dug along the outside as the box en- 

 tered the soil, these frames were forced their whole depth into (lie 

 soil. A heavy flat seel ion of boiler iron, the edge sharpened, was 



'Annual lioport of Executiye Board and of llio City Engineer of Rochester. 



