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) 

 winch 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. 



