20 BULLETIN 852, U. S. DEPARTMENT OF AGRICULTURE. 
OFFICE EQUIPMENT AND METHODS. 
Original multiplication, division, and addition were performed on 
mechanical devices, except in the computation of a few coefficients, 
where slide rules sufficed. Checking was done by 20-inch slide rules 
and graphic methods. Estimate diagrams were checked by proving 
random examples. 
Office procedure. — Where water columns were used at both ends of 
the reach of pipe tested the loss of head in the pipe for the given 
velocity was the difference in elevation between the top of the mean 
water column at gauge No. 1 and the top of the mean column of 
gauge No. 2. Where a mercury manometer was used at one or both 
of the gauges the equivalent water column for each reading of the 
mercury column was computed. The mean of the elevations of the 
tops of the equivalent water columns was accepted as the elevation 
for that gauge. The loss of head was then computed as before. 
Standard methods were employed in computing current-meter data 
or weir discharge. Where color was used in timing the velocity of 
the water, the time was computed as from the instant of injection to 
the mean between first sight and last appearance of the color at the 
outlet. 
ELEMENTS OF EXPERIMENTS FOR THE DETERMINATION OF FRICTION 
LOSSES IN CONCRETE PIPES, FLOWING FULL. 
In the following pages two tables are arranged (Tables 3 and 4) 
which give the elements of all known observations on concrete pipes 
under pressure. The various series are arranged in ascending sizes 
of pipe and within one series the observations are arranged in 
ascending order of velocities. 
EXPLANATORY NOTES ON TABLE 3. 
Column 1 gives the consecutive numbers of the pipes followed in 
column 1, Table 4, also in the discussions in the following pages and 
in the Appendix. The small letter a after the numbers refers to dis- 
cussion in the Appendix. Experiments conducted by this depart- 
ment are discussed in the text while the essential data secured from 
other sources are abstracted in the Appendix. 
Column 2 shows the authority (see also column 2, Table 4) the series 
number where such was carried, together with the date of the test. 
N refers to H. D. Newell, project manager, United States Recla- 
mation Service, Umatilla project, Oregon. 
F refers to J. T. Fanning. 
B refers to the late Henry Bazin, France. 
AB refers to Prof. A. Budau, Austria. 
RDJ refers to R. D. Johnston, consulting engineer, Ontario Power 
Co., Canada. 
