88 BULLETIN 852, U. S. DEPARTMENT OF AGRICULTURE. 



The discharge was measured with a current meter. Depths were 

 determined from a horizontal straightedge. On account of rough 

 topography, floor elevations as furnished by the company were 

 accepted in computing the slope of the water surface. The value of 

 n was found to be 0.0127. (See p. 11 for Mr. Lippincott's conclusions.) 



No. 59, Experiment JBL-2. — Tunnel No. 23 of the same system as 

 above. — Of this experiment Mr. Lippincott writes: 1 



This test was made at tunnel No. 23 of the same system. Conditions were similar 

 in all respects, except for slight curves just below north portal and above south portal. 

 The length of tunnel is 318 feet and grade of floor 0.00095 foot per foot; n here was 0.0115. 



(See p. 11 for Mr. Lippincott's conclusions.) 



No. 60, Experiments JBL-5 and 6. — Main supply conduit for Los 

 Angeles, Calif. — These tests are described as follows: 



These were on the main supply conduit for Los Angeles, near the old ostrich farm, 

 several miles north of Los Angeles. It is covered and has been in use four years. The 

 length of section was 700 feet, being between two manholes. A curve occurred on this 

 section. The wetted perimeter was very smooth, apparently of a 1 to 3 cement 

 mortar. There was no sand, moss, or vegetable growth of any kind. Experiment 5 

 was at the upper and 6 at the lower manhole. The grade of the floor was the 

 same as that of the water surface. The surface was a cement plaster on concrete. 

 The value of n here was 0.0112 and 0.0109. (See p. 11.) 



No. 61, Experiment AFB-1. — Loch Katrine Aqueduct, Glasgow, 

 Scotland. — -The concrete-lined portion of the new aqueduct from 

 Loch Katrine to Glasgow was tested in 1895 by A. F. Bruce. 2 Of 

 the construction he writes: 



Open frames of 6-inch by 2-inch battens were first placed in position and three- 

 fourth-inch tongued and grooved boards, smeared with soft soap, nailed to the frames 

 horizontally as the concrete was filled in. Every possible precaution was taken by 

 working with spades to obtain a good face, and except where some defects showed 

 themselves, no redressing was afterwards necessary. 



About 53 per cent of the aqueduct was lined. The section units 

 were from 12 to 15 feet long, generally 12 feet. The reach tested 

 was straight. The quantity of water was measured over a weir. 

 The depths of water in the aqueduct were read on gauge rods in the 

 chambers. Water at the lower end was checked by the fact that 

 one siphon gate below the reach under test was closed. 



The lined section is 9 feet 1 inch wide on the bottom, with the 

 invert dished 6 inches. The sides batter until at the spring line the 

 width is 10 feet. The rise of the arch is 3 feet. Depth over all is 

 9 feet. 



Most of the observations indicate a correct value of n for this new 

 channel of about 0.0124. 



No. 62, Experiment P-l. — Aqueduct of the Serrino, Naples,Italy. — 

 In 1896 Perrone wrote 3 of a test made on the aqueduct of the Ser- 

 rino, at Naples, Italy. This channel, of pure cement, polished, had 

 vertical sides and elliptical bottom. The discharge was measured 

 with a current meter. The value of n, being but 0.0107, indicates 

 the workmanship and lack of slime to be all that the short descrip- 

 tion implies. 



1 Observations to determine the value of Cand n as used in the Kutter formula by J. B. Lippincott, 

 Engin. News, June 6, 1907, vol. 57, p. 012. 



2 Observation on trie Flow of Water in the New Aqueduct from Loch Katrine; Glasgow Corporation 

 Waterworks, A. F. Bruce, Paper No. 2921, l'ro. Inst. Civil Engineers, Vol. CXXIII, 1895-96, part 1, p. 

 410. 



3 Zoppi, Sul Volturno, Carte ilydrographique d'ltalia; The Flow of Water, by Louis Schmeer, New York 

 1909, pp. 46, 80, 93. 



