To measure the velocity of water flowing at any 
point in a stream, the hydrographer need only 
position his meter at the desired point and count the 
number of revolutions the impeller makes during 
whatever period of time is provided for in the table— 
usually 40 to 70 seconds. He can accomplish that 
operation either by making an actual count of the 
clicks he hears in a headphone connected to the meter 
or by the method used by Price, namely, using an 
electric register, the early expression used to describe 
an electrical counter. After determining that figure, 
he would consult the rating table to determine the 
magnitude in feet per second of the water’s velocity at 
the point where his meter was positioned. Many 
velocity observations are needed because of the vari- 
ations in velocity which prevail throughout the cross 
section of every stream. The velocity is usually high- 
est near the surface at midstream; from that point, it 
gradually becomes slower and slower as the bottom 
and sides of the streambed are approached. 
During the past 40 or 50 years, most of the Govern- 
ment-owned current meters have been rated at the 
National Bureau of Standards. Such service was not 
available to Price in 1880, so the method he used 
under exceptionally trying circumstances is of con- 
siderable interest. Here is the description he wrote 
for the Journal of the Western Society of Engineers’ on 
how six ratings of his Ellis meter were made on cold 
days during the winter of 1880-1881: 
‘The meter was first rated in a lake of still water, through 
the ice. To do this successfully, an opening should be cut 
in the ice one foot wide and 250 feet long. The meter 
should be attached to its rod and weight, and suspended 
two or three feet below the ice from a sled which straddles 
the opening, and which carries the observer with his 
battery, register, and stop watch. ‘The ice must be made 
level where the sled runners are to pass, so the meter will 
be carried without any up and down movement. A base 
line of 200 feet should be measured along the opening, and 
each end should be marked by a range made by two 
flags at right angles with it. The sled should be drawn 
back and forth at low, medium, and high velocities, the 
stop watch and register being started on the first range 
line and stopped on the second. Several ratings like this 
were made by the writer during the winter of 1880-1881. 
In the same article, Price also described how he had 
made his measurements of streamflow when the river 
was covered with ice: 
7 Wituiam G. Price, “Gauging of Streams,” Journal of the 
Western Society of Engineers (1898), vol. 3, p. 1026. 
46 BULLETIN 252: 
[A house was built] just large enough for one man to sit 
inside, leaving room at the end for a very small stove,— 
and room at the other end to lower the meter into the 
water through a trap door. The sled had board runners, 
curved to run forward and back, and had a rope at each 
end to draw it by. The house consisted of a light wood 
frame, which was covered on sides and top with heavy 
canvas, and had a canvas door, all of which was given a 
coat of linseed oil. A reel near the roof, at one end, 
carried the steel meter-suspending rope and _ insulated 
wire. The shaft of the reel passed through the side of the 
house, and there was a crank-ratchet and pawl on the 
outside. The suspending rope and insulating wire were 
connected with copper rings on the reel, and springs made 
contact with these rings and completed the electric circuit 
to the meter, register, and battery. ‘Two men were re- 
quired to measure the discharge, one to sit inside and 
record the soundings, registrations, and time,—and the 
other to cut holes in the ice, draw the sled, feed the fire, 
and turn the outside crank when the meter was to be 
raised or lowered. Holes were cut in the ice in a line 
across the river, and measurements were taken at mid- 
depth, for the discharge. Many vertical velocity measure- 
ments were also taken, so as to determine the correction 
required to reduce the observed mid-depth velocity to the 
mean velocity. 
Soon after October 24, 1881, Price’s party of stream 
gagers left Clayton for similar work on the Ohio River 
at Paducah, Kentucky. By December 22 he had 
established a gage there and had selected a suitable 
section in the river for making discharge measure- 
ments. During the following month, January 1882, 
Price conceived the design of his first current meter. 
The circumstances relating to his invention were 
described in a letter he wrote on April 20, 1927, to 
Nathan C. Grover, then chief hydraulic engineer of 
the United States Geological Survey: 
In January, 1882, I began measuring the discharge of 
the Ohio, at Paducah, Kentucky, under orders of Captain 
Smith S. Leach, Corps of Engineers, U.S.A., who was 
Secretary of the Mississippi River Commission. My 
equipment included a meter which was designed by 
General Ellis and another which was designed by Clemens 
Herschel. 
The Herschel meter was of the propeller type, having a 
horizontal shaft,—and there were no means for excluding 
water from its bearings. 
The Ellis meter had a cupped wheel which revolved in a 
horizontal plane,—and there was no provision for exclud- 
ing water from its vertical-shaft bearings. 
I rated these meters in clear, still water, and the plotted 
ratings indicated that they would give accurate measure- 
ments. 
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