kewell.] SHENANDOAH AND POTOMAC RIVERS. 89 
MILLVILLE STATION, ON THE SHENANDOAH RIVER. 
This station is on the Shenandoah River, at Millville, W. Va., 4 miles 
above Harpers Ferry. The gage consists of a vertical board nailed to 
the projecting trunk of a tree and firmly fastened by cross braces. The 
bench mark consists of a notch cut in the tree opposite the 8-foot mark 
of the gage. The channel is rocky and not liable to change. Meas- 
urements are made from a small box, or car, 2 feet wide, 3.5 feet long, and 
3 feet high, suspended from a 1^-inch cable which has been erected by 
private parties for use of a ferry. 
POINT OF ROCKS STATION, ON POTOMAC RIVER. 
This station is at the toll bridge over the Potomac River near Point 
of Rocks, Md. It is equipped with a wire gage, which is read from the 
bridge floor, measurements of discharge being made from this bridge. 
CHAIN BRIDGE STATION, ON POTOMAC RIVER. 
Readings of river height at this point were begun on May 4, 1891, 
and continued until the end of 1803, when they were discontinued, 
owing to the difficulty of obtaining an observer. They were taken up 
again on December 18, 1894. The height of water is measured by 
means of a wire gage having a horizontal scale which reads from 10 to 
30 feet. On March 20, 1895, this was supplemented by a cylindrical 
nilometer. Measurements of discharge are made from the bridge, but 
have not been wholly satisfactory, owing to the great velocity at times 
of high water. Computations of discharge of the river, based upon 
measurements at this point and upon a record kept at Great Falls, 
have been published in the Fourteenth Annual Report of this Survey, 
Part II, pages 135-137, giving the monthly flow from 1886 to 1893, 
inclusive. 
LIST OF DISCHARGE MEASUREMENTS OF VARIOUS STREAMS IN 
THE UNITED STATES. 
The following list gives, in brief, the results of individual stream 
measurements made at various stations established by this Survey, and 
at other points where it has been ascertained that such work has been 
carried on. For convenience of reference these are arranged in chrono- 
logic order. Many of them have been discussed more fully under the 
descriptions of the different river stations. In nearly all instances 
these measurements were made by means of current meters, by which 
the velocity of various portions of the current was ascertained, the 
meter being placed at regular intervals across the stream and near 
the surface, bottom, and in intermediate positions. The depth of the 
stream having been ascertained by sounding line or pole, and the width 
measured directly, the discharge for each portion was computed and 
the results were summed up as shown in the table. This list gives the 
