12 BULLETIN 376, U. S. DEPARTMENT OF AGEICULTUKE. 
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 1 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 55| 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 55| inches. The positions of platted points 
for the 55f -inch pipe (Nos. 45 and 46) shown on Plates VI and VII, 
when compared 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. 2 
In the same discussion 3 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 
i Trans. Amer. Soc. Civ. Engin., 74 (1911), p. 411. 2 id., p . 452. 3 id., p. 459. 
