482 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 



pounding water, with special attention to percolating losses through 

 such structures, was begun with a view to securing greater safety 

 and efficiency. The project is cooperative in an informal way with 

 the United States Reclamation Service, and several owners of struc- 

 tures where percolation losses have been costly are cooperating in the 

 investigation. 



A field study of the various types of chutes and drops in canals 

 was practically completed. Special attention was given to the prob- 

 lem of eliminating erosion of banks of canals above and below the 

 structures, a defect which has caused great damage to canals in the 

 past. The results are nearly ready for publication. 



A study of the rates of run-off that may be expected from drained 

 irrigated land was begun. Many drainage districts have completed 

 or are just completing their drainage systems, and these afford un- 

 usual opportunity for the collection of data in regard to the amount 

 of water that must be removed under different conditions to provide 

 satisfactory drainage of irrigated lands that have been or are becom- 

 ing water-logged. Such data are of great value to the engineer in- 

 trusted with the design of drainage structures and when obtained 

 will permit of much more accurate designing and consequent greater 

 efficiency at lower cost than it has been possible to obtain in the past. 



Field investigations for a bulletin on drainage structures were 

 completed during the year, and the manuscript is partly prepared. 



In response to a request from the sugar planters of Hawaii ar- 

 rangements were made by which an engineer was detailed to make an 

 examination of drainage conditions on a number of plantations in 

 the Hawaiian Islands. The field investigations were completed, and 

 a report thereon is in preparation. The investigations indicate that 

 with improved drainage conditions some lands which are not now 

 well adapted to the raising of sugar cane may be made suitable for 

 that crop. 



In cooperation with the Colorado Experiment Station the follow- 

 ing investigations were continued : 



1. Hydraulic experiments at Fort Collins. The major work in- 

 volved tests of various types of water-measuring devices and the 

 development of new ones. Considerable work was done on a weir 

 of the Hershel hollow-crest type in an effort to develop a satisfac- 

 tory device which will register accurately when partly submerged 

 by back water; conclusive results were not obtained, and the work 

 will be continued during the coming year on a modified form of 

 this weir. The activities embraced also : Perfecting of a device 

 which will accurately divide or apportion a stream of water in cer- 

 tain ratios: assembling under suitable conditions at the hydraulic 

 laboratory various types of water-level recording and measuring de- 

 vices for comparison as to accuracy, reliability, sensitiveness, action 

 under varying conditions of increasing and decreasing head, etc. 

 A manuscript for a bulletin giving the results of tests on the water- 

 level recording instruments is nearly completed. 



2. A study of evaporation from water surfaces and of the various 

 factors which influence the rate of evaporation was made for the 

 purpose of developing an empirical formula by which the amount 

 of water evaporated from a water surface in a given time can be de- 

 termined with reasonable accuracy. The work is being carried on in 

 both laboratory and field. In the work in the laboratory it is possi- 



