16 BULLETIN 194^ U. S, DEPARTMENT OF AGEICULTUEE. 



ELEMENTS OF FIELD TESTS TO DETERMINE RETARDATION FACTORS 

 IN KUTTER AND CHEZY FORMULAS. 



In the following pages are arranged a table (Table I) showing the 

 hydraulic elements followed by text matter giving brief descriptions 

 of the general conditions obtaining at the canals measured by the 

 writer and his associates during the season of 1913 with a few tests 

 made in the two preceding years. In both the table and descriptions 

 the experiments are arranged in groups according to the material of 

 the containing channel, while the order within each group follows an 

 ascending value of n, except where several tests were made on the 

 same reach of canal with various discharges of water, in which case 

 tests on that particular reach are not separated. 



EXPLANATORY NOTES ON TABLE I. 



Column 1 gives the consecutive numbers, which refer to the order followed in the 

 discussions in the following pages and in the appendix. 



The small letter a after the number refers to the appendix. 



Previously unpublished experiments by members of the force of this office are 

 discussed in the text, while the essential data secured from other sources are abstracted 

 in the appendix. 



Column 2 shows the authority and his experiment number where such was carried. 

 The symbols referring to members of this force are as follows: 



B refers to Don H. Bark, irrigation engineer in charge of work for this office in 

 Idaho. 



F refers to Burton P. Fleming, of the department of mechanical engineering, State 

 University of Iowa. 



G refers to W. B. Gregory, irrigation engineer, head of department of experimental 

 engineering, Tulane University, La. 



H refers to Sidney T. Harding, at that time irrigation engineer in charge of work for 

 this office in Montana. 



McL refers to Walter W. McLaughlin, at that time imgation engineer in charge of 

 work for this office in Utah. 



S refers to the writer, Fred C. Scobey, irrigation engineer at large, in charge of 

 experiments on the flow of water in channels. 



The symbols referring to other sources, most of which are publications, are as follows: 



PS refers to the United States Reclamation Service, through whose courtesy we 

 were allowed access to the records of experiments conducted by various members of 

 the service. 



JBL refers to J. B. Lippincott.^ 



\1IG refers to V. M. Cone, in charge of the work of this office in Colorado.^ 



SF refers to Samuel Fortier, Chief of Irrigation Investigations. ^ 



W refers to C. C. Williams, professor of railway engineering. University of Kansas.* 



Column 3 refers to the classification, showing the relative weight to be given the 

 data, A signifying first-class conditions for experimentation. B and C show second 

 and third class conditions, such as too short a reach, a doubtful method of measm-ing 

 discharge, proximity of disturbing features in the canal, and so on. 



Column 5 shows the general shape of the canal cross section, referred to in figure 2. 

 When considered in connection with columns 6, 7, 8, 9, and 11, an idea of the water 

 section may be' secured. 



1 Tests described in Engin. News, 57 (1907), No. 23, p. 612. 



2 Tests selected from Colorado Sta. Bui. 194 (1914). 



3 Tests selected from U. S. Geol. Survey, Water-Supply and Irrig. Paper 43 (190i). 

 * Tests described in Univ. Colo. Studies, 7 (1910), No. 4, p. 237. 



