270 GROVE KARL GILBERT— DAVIS IMemoib V\£xx£ 



But let no philologist imagine that "right smart" is New York State dialect because it is 

 here used by a man of Rochester birth. As a result of this careful examination, the first debris 

 report appears to contain citations of a larger number of foreign authors than are to be found 

 in all the rest of Gilbert's writings put together. The completion of the report is thus referred to : 



Friday the 13th [of June] 1913, was not an unlucky day for me, but one of exceptional plesure, for I turnd 

 in a report on which I have been at work more than two years. The title is " Transportation of Debris by Run- 

 ning Water", and it will be printed as a "Professional Paper." 



It was probably a consciousness of having thus entered upon a new field of study that led 

 Gilbert to wish to have his manuscript looked over by an expert: 



I want to have it criticized by some very competent man who will express his mind freely. Talkt with 



a little when I was in Ithaca, but am a little afraid he would be too polite to be candid on its weak points. 



In the judgment of readers after the report was published there were no weak points in tbe 

 treatment of the material under discussion; if the report had a defect, it lay in the difficulty 

 of applying its results to actual problems in river engineering, a difficulty which Gilbert himself 

 saw and lamented. It is because of the abstract nature of its results that this study seems not 

 to deserve so high a rank as its sequel, in which the actual distribution of mining debris was 

 examined. Toward the close of this elaborate research Gilbert wrote his son a simple rule 

 based on his own experience for the estimation of river discharge, essentially as follows: (1) 

 Select a direct reach of uniform flow; (2) measure the cross section in square feet at a few points 

 and take their average; (3) measure a base line along the bank; (4) throw a float, such as a 

 tree branch with leaves, into midstream, time its passage along the base line and thus determine 

 the surface velocity in feet per second ; then (5) the discharge in cubic feet per second = 0.8 X sec- 

 tional area X surface velocity. 



DISTRIBUTION OF DEBRIS 



Gilbert's second report upon his work in California deserves to rank with the finest of his 

 studies. There is a brilliancy about it that even he rarely equaled. It embodies an exception- 

 ally fine treatment of a high-grade problem in river engineering based upon a secure physio- 

 graphic foundation; a fine treatment, because of its breadth and elegance; an exceptionally 

 fine treatment, because the combination of thorough competence that Gilbert possessed both 

 in engineering and in physiography is rarely encountered. Unlike the first report, which is 

 largely experimental and theoretical, the second gives many actual examples of the distribution 

 of hydraulic-mining debris, which is not by any means limited to the mountains, as its title, 

 "Hydraulic-mining debris in the Sierra Nevada," would suggest, but which, as already noted, 

 extends its consideration across the fluviatile plain or valley of California and through San 

 Francisco Bay to the tidal bar outside of the Golden Gate. Yet in spite of its high quality, 

 the second report is not so well known as it deserves to be; perhaps because it was preceded by 

 the first, which by reason of its largely mathematical treatment was not generally readable and 

 may therefore have discouraged examination of the second; and perhaps also because, unlike 

 the Henry Mountains report and the Bonneville monograph, which appeared at an earlier time 

 when survey publications were not so very numerous, this important report was only one in a 

 great annual flood. Nevertheless, the second report deserves to rank in originality with the 

 Henry Mountains volume, to which it is similar in size, and it is a close second to the Bonneville 

 monograph, which it almost rivals in thoroughness. And as the last completed study of a great 

 geologist, over 70 years old at the time it was issued, the report merits attentive reading by all 

 his legion of admirers. Yet it would have been surpassed by the unfinished report on the basin 

 ranges had that not been interrupted a few years later by Gilbert's death. 



Like the report on the "Transportation of hychauhc-mining debris," the report on its 

 "Distribution" entailed an immense amount of study; but here the greatest part of the obser- 

 vational work was in the field instead of in the laboratory, and the discussion of the observations 

 involved chiefly a most ingenious train of physiographic inferences, instead of a laborious series 

 of mathematical computations. The field work, begun in 1905, was long interrupted by the 

 "Transportation" study, as well as by the year of illness. It was resumed in 1913, when 

 California was revisited. In July of that year, Gilbert wrote to his son: 



