16 BULLETIN 194, TJ. S. DEPAETMENT OF AGRICULTURE. 
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Previously unpublished experiments by members of the force of this office are 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 irrigation 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: 
RS 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. 1 
VMC refers to V. M. Cone, in charge of the work of this office in Colorado. 2 
SF refers to Samuel Fortier, Chief of Irrigation Investigations. 3 
W refers to C. C. Williams, professor of railway engineering, University of Kansas. 4 
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 measuring 
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. 
i Tests described in Engin. News, 57 (1907), No. 23, p. 612. 
2 Tests selected from Colorado Sta. Bui. 194 (1914). 
s Tests selected from U. S. Geol. Survey, Water-Supply and Irrig. Paper 43 (1901). 
* Tests described in Univ. Colo, Studies, 7 (1910), No. 4, p. 237, 
