682 



EXPEEIMEKT STATION RECOED. 



[Vol. 31 



distance of at least 35 diameters of the downstream section, below the enlarge 

 ment must be included. The value of the coefficient K is very nearly the sam^ 

 in the two cases of enlargement investigated, and is approximately 0.97. 



" The Pitot tube reversed, i. e., the impact point turned downstream, gives 

 negative pressure head which, reduced to velocity, negative, gives a value whose 

 ratio with the velocity in the upstream direction is fairly constant for any given 

 form of tube. But the relative values of the downstream readings to the ui 

 stream readings for different forms of tubes vary greatly. The maximum nega 

 tive pressure or suction action at the impact point of the Pitot tube occurs whei 

 the direction of the axis of the opening Is approximately pei-pendicular to th^ 

 direction of flow." 



Value of Kutter's "n" for metal flumes (Reclam. Rec. [U. S.], 8 (1917) 

 No. 1, p. 37). — Tests made on the North Plattt- and Uncompahgre irrigation" 

 projects to determine the value of the coefficient n in Kutter's formula for metal 

 flumes are reported. " The results indicate that 0.012 is a fair average value 

 for n in flumes with smooth interior, and that 0.013 may be considered amply 

 safe for design." 



HoldiBg power of nails (Engin. Rec, 75 (1917), No. 2, p. 71). — From experi- 

 ments on the holding power of 16d. and 20d. nails in a direction perpendicular 

 to the length of the nail in which 2 by 12 in. yellow pine planks were nailed to 

 fir sills and sheared off, a safe loading of 210 lbs. for 16d. and 250 lbs. for 20d. 

 nails was assumed for use in the heel plates of the wooden flumes on the West 

 Okanogan Irrigation Project. 



Friction of bronze on bronze (Reclam. Rec. [U. S.], 8 (1917), No. 1, p. S6).— 

 Experiments on the coefficient of friction of bronze on bronze to be used in 

 estimating the power required in the operating mechanism for large high- 

 pressure sluice gates are reported. The tests were made on gates at the Path- 

 finder, Arrowrock, and Elephant Butte dams, all of which are provided with 

 cast bronze bearing surfaces and are operated by oil pressure on pistons moving 

 in cylinders mounted on the gate bodies. The results are given in the following 

 table : 



Oate tests. 



Beport on irrigation surveys and Inspections, 1915—16 (Dept. Int. Canada, 

 Irrig. Branch Rpt. 1915-16, pp. 86, pis. Jf). — This includes the reports of the 

 Superintendent and Commissioner of Irrigation and of the chief field in- 

 spector ; a summary report on duty of water and irrigation crop reports ; and 

 reports on bench marks, on the C3rpress Hills, Western Maple Creek, and 

 Calgary irrigation districts, on international waterways, and on the Leth- 

 bridge Northern Irrigation Project, for 1915-16. 



State Rivers and Water Supply Commission [of Victoria], eleventh annual 

 report, 1915—16 (Victaria Rivers and Water Supply Com. Ann. Rpt., 11 (1916), 

 pp. 39, pi. 1, fig. 1). — A statement of the work and expenditures of the commia- 

 slon for the financial year 1915-16, and estimates for 191&-17, 



