12 BULLETIN 376, U. S. DEPARTMENT OF AGRICULTURE. 



the results might still agree with a weir test quite closely and yet 

 include an error as to the velocity. 



The writer dwells on this discussion for the reason that he has 

 before him three catalogues of prominent pipe makers, each of which 

 claims a very high efficiency for wood pipe (to the consequent dis- 

 paragement of iron and steel pipe), basing this claim on one question- 

 able series of tests and ignoring the other tests mentioned above for 

 the probable reason that the most of the latter show the capacities 

 of wood and new iron pipe to be more nearly the same. 



In 1911 E. A. Moritz^ offered the results of experiments which 

 were quite complete between pipes 4 inches and 22 inches in diameter, 

 with a gap then to one pipe 55f inches in diameter. He used much 

 the same methods (in fact, much of the same equipment) which were 

 used on the Ogden tests. 



Rejecting all previous experiments and his own series on the 

 22-inch pipe (No. 28), Moritz developed the formulas given on page 6. 

 This left a very complete set of experiments between 4 and 18 inches 

 but with a gap from 18 to 55f inches. The positions of platted points 

 for the 55f-inch pipe (Nos. 45 and 46) shown on Plates VI and VII, 

 when com.pared with corresponding points for other pipes, all indi- 

 cate that this pipe was exceptionally smooth. So much weight was 

 given the tests on this pipe, being the only tests on large pipe which 

 were accepted, that the formulas derived from the experiments indi- 

 cate a greater carrying capacity for wood pipe generally and large 

 diameter wood pipe particularly than a study of all tests shows to be 

 warranted. 



In the discussion of Moritz's article, R. G. Dieck writes: 



The use of the Kutter formula in pipe design has always been questionable, even 

 though its ease of application, in default of a more convenient formula, has commended 

 it * * *. It is evident from the Sunnyside experiments that an adjustment in 

 the ideas of hydraulicians on this point is bound to come. * * * When the dis- 

 charge varies, all other conditions being the same, the value of n also varies; hence in 

 its present form, the Kutter formula can not be considered a true statement of condi- 

 tions.^ 



In the same discussion ^ Rudolph Hering states that he ''recognized 

 as well as did Mr. Kutter himself, almost at the outset, that n was 

 not to be considered a precise and unvarying constant." The writer 

 will take up the comparison between the Kutter and the new expo- 

 nential formula later (p. 56). 



In the same discussion Gardner S. Williams objects to the incon- 

 sistency of the profession in introducing inches into a formula other- 

 wise expressed in feet and decimals. The writer agrees in this, but 

 the manufacture of iron, steel, clay, and wood pipe has been so long 



1 Trans. Amer. Soc. Civ. Engin., 74 (1911), p. 411. 2 id., p. 452. s id., p. 459. 



