44 PROCEEDINGS OF THE AMERICAN ACADEMY 



and these heights may be expressed approximately at Station No. 7 

 by 0.0002 U\ and at Station No. 10 by 0.0005 U\ 



On the other hand, on the west side at Station No. 7 and east side 

 at Station No. 10, where the passages go out up stream, the surface 

 of the piezometric reservoir at Station No. 7 stands lower than 

 the surface of the stream by amounts expressed approximately by 

 0.00025 U'\ While at Station No. 10, the surface in the reservoir is 

 slightly above and below that of the stream, in no case more than 

 0.004 ft., and the mean result for all of the velocities is very nearly 

 zero. 



If there were any lowering of the piezometer by the action of 

 cohesion at its base, it would follow that with orifices having passages 

 so very favorable to drawing water from the reservoir, as in the two 

 cases just considered, the lowering would be much greater than the 

 raising above the stream in the two previous cases; but the lowering 

 being really less than the raising tends to the conclusion that there is 

 no lowering due to cohesion at the orifice. 



The raising of the piezometric column three per cent of the head 

 that would produce the velocity of the stream, and the lowering of 

 one and one-half per cent of the same head by the difference in direc- 

 tion of the passage, without any perceptible variation of the plane of 

 the orifice from that of the side, indicate that, either from impercep- 

 tible variations in the plane of the orifice, or from sinuosity of cur- 

 rent, such inclined passages are not to be relied upon for accurate 

 results. 



Orifices projecting into the Stream. Passages inclined. 



At Station No. 2, a hole was bored through each side of the trough, 

 making with the inner face a horizontal angle of 48°, up stream on 

 the west side and down stream on the east side. Into these holes 

 were fitted brass pipes, 0.049 ft. in diameter outside, and 0.043 ft. in 

 diameter inside, having the inner ends finished smooth with square 

 edges. These pipes projected into the trough, so that the intersec- 

 tion of the plane of the end of each with the plane of the side of 

 the trough was very nearly a tangent to the outer circumference of 

 the end. 



The distance from the plane of the side to the point of the outer 

 circumference of the end farthest removed was 0.033 ft., and to the 

 corresponding point of the inner circumference was 0.031 ft. 



At Station No. 6 were .other projections into the trough. Two 

 brass castings were made, each consisting of a plate 0.083 ft. high, 



