90 



BULLETIN 37G, U. S. DEPAETMENT OF AGRICULTURE. 



reduced from 1. 25 to 1.17 until the field of larger pipes has been more fully covered. 



H=0.43 v^-* 

 The formula ^7725 gives practically aa correct results as the author's formula 



and conforms much better with the results developed by previous experimenters. 



It is conceded that the arguments presented herein are rather unscientific, but we 

 are dealing with a problem that is more practical than scientific, and expediency 

 should be given as much weight therein as science. The engineer should not strive 

 for an impossible accuracy or an artificial consistency in his essentially practical 

 operations. The writer feels that the author would be doing the engineering profession 

 a greater good if he would depart to a smaller extent in his formula from the factors 

 that have been developed by other experimenters before him. 



Dr. Schoder: After the first reading of the paper the writer is inclined toward a 

 somewhat detailed discussion of numerous points that seem open to reasonable differ- 

 ences of opinion. However, after again reading the paper, most of these points seem 

 to be aside from the main argiunent that is advanced somewhat directly and some- 

 what by implication in the paper. Consequently the writer's comments will deal 

 rather with the question it seems proper to ask: "Does the paper sufficiently empha- 

 size the relations of the facts therein established for wood-stave pipes to the facts for 

 pipes of all materials? " 



This suggests the query: " Is a special formula for wood-stave or any other 'particular 

 material proper or practically desirable in the light of information now before the engi- 

 neering public?" The author's paper is a very important contribution toward such 

 information. It remains to make the general examination and comparison suggested. 



Concerning the new data gathered by the author, the writer would sum up his esti- 

 mate and appreciation: (1) The field difficulties were many and serious. (2) The 

 measurements, in the main, appear to be reliable. 



Comparison of the data on wood-stave pipes with the data on pipes of all materials. 

 The author states (p. 51) that the exponent of the velocity ranges from 1.56 to 2.31 

 and that he is unable to find any law for this variation for the wood stave pipe data. 

 It is interesting to examine these exponents as given in the nicely arranged Table 3. 



1"-10" 



12"-24" 



30"-162" 



1.723 



1.738 



1.56 



1.895 



1.730 



1.67 



1.808 



1.870 



1.70 



1.877 



1.703 



2.31 



1.847 



2.176 



1.719 



1.724 





1.696 



1.590 





1.747 



1.766 





1.618 



1.875 





1.973 

 1.690 

 1.891 

 2.143 



It seems to the writer that "confusion' will be worse confounded" by the apparent 

 sanction of a United States governmental department to a formula and diagrams or 

 tables based thereon, particularly applicable to wood-stave pipes, when the data, 

 according to the author's own statements of factors of safety on page 66, and particularly 

 in column 19 of Table 2, show such large departures from the results by the formula, 

 and when there is nothing in the data on wood-stave pipes that distinguishes such 

 pipes from the data on iron, steel, brick, concrete, or other pipes. 



In other words, if all the data presented on wood-stave pipes are plotted on Plate 

 XI, IVans. Amer. Soc. Civ. Engin., vol. 51, or on figure 2, Cornell Civil Engineer, 

 May, 1910, or even if the data for all steel and iron pipes be added to the author's 

 figure 4, the conclusion seems to be irresistible that the pipes used in engineering 

 practice for the conveyance of water can not be segregated, as to hydraulic resistance 



