THE PLOW OF WATER IN WOOD-STAVE PIPE. 13 



conducted on these units that it appears best to construct separate 

 formulas with terms in both inches and feet. 



Also in the same discussion^ J. S. Moore, who aided in the experi- 

 ments and computation of the Moritz data, offers tests on 48f and 

 31-inch pipes (Nos. 43 and 36). The 48|-inch pipe appears to have 

 been very smooth and the tests confirm the Moritz formulas. How- 

 ever, it must be borne in mind that this pipe is part of the same 

 siphon and subject to the same conditions as those affecting the 55f- 

 inch pipe which contributed so largely to the data from which the 

 Moritz formulas were derived. Advocating the use of all previous 

 data accepted as criteria, Moore suggests the intercept line for the 

 exponential formula as shown by the dash line in figure 4. This 

 line approaches the position of the intercept fine for the new formula 

 which considers all reliable data. 



RECAPITULATION. 



The above outline indicates that 25 years ago Kutter's formula, 

 with a value of n of 0.010, was accepted as accurate in the design of 

 wood pipes. As tests were made on larger sizes of pipe, higher values 

 of n were found. These results were not accepted unreservedly, 

 however; rather were the experiments discredited by some designers 

 on the grounds that conditions in the pipes were not properly ascer- 

 tained or that methods of making observations were erroneous. 

 The experimenters themselves suggest that perhaps a constant value 

 of n should not be used; that is, that Kutter's formula does not 

 apply if a constant value of n is to be taken. The data were too 

 meager to develop the variation in n with the diverse elements. 



As data accumulated authorities suggested interpreting results 

 by exponential formulas; but not being well known this method was 

 not extensively accepted until used by Moritz in interpreting his own 

 results. He attempted to compare his formulas with the results of 

 other experimenters but found this "a, diflB.cult and discouraging 

 problem." This was true because all previous data on large pipes 

 showed a much smaller relative capacity than the one pipe contribut- 

 ing so largely to his formulas. Though but tentatively offered by 

 Moritz, his formulas appeared to be the best available and have been 

 extensively accepted, in spite of the fact that Moore, who was per- 

 fectly familiar with the Moritz tests, suggests a formula that more 

 nearly fits all previous observations. 



In the following pages of this publication, particularly beginning on 

 page 28, the writer will endeavor to show analytically the following: 



1. That an exponential formula most nearly applies to the flow of 

 water in wood-stave pipes. 



I Trans. Amer. Soe. Civ. Engin., 74 (1911), p. 463, 



