8 
Transactions Texas Academy of Science. 
[40] 
The only thing left to do was to measure the surface velocities, and after- 
wards to apply a suitable coefficient, and even then the drift sometimes 
made it hazardous to attempt to use the meter. For high stages the meter 
readings were checked by float observations. It must, therefore, be 
remembered that for high velocities the results obtained may be affected 
by a relatively large probable error. 
The drainage area of the Brazos river above the Jones bridge, count- 
ing in that portion of the Llano Estacado that sometimes sheds water 
towards the river, is about 37,400 square miles, or if that portion of the 
area that lies above 3000 feet elevation be excluded, as probably contrib- 
uting but little to the discharge, it will be about 30,150 square miles. 
The drainage area of the Wichita river, above Wichita Falls; is about 
3050 or 3060 square miles and the greatest discharge of which I secured 
a measurement was 16,740 cubic feet per second, which was on July 21, 
1900. The gauge then read 12.1 feet, but during last December the river 
was much higher, with a discharge perhaps two or three times as great 
for a short time. The smallest measured discharge was obtained on July 
16, 1900, and amounted to sixty-one cubic feet per second. The gauge 
then read 1.65 feet, and while the gauge has read as low is 1.4 feet it is 
not likely that the discharge has ever fallen below fifty or fifty-five cubic 
feet per second. I was unable to secure an observer to make daily gauge 
readings on the Wichita river until February of this year, since which 
time such readings have been taken. I have worked up the results for 
only seven months and these are given below : 
RESULTS OF DISCHARGE AND SILT MEASUREMENTS ON THE WICHITA RIVER. 
Month. 
February 
March . . 
April . . . 
May 
June . . . 
July 
August . 
Discharge in 
Silt 
acre feet. 
acre f 
5,970 
0 
9,530 
0 
78,550 
995 
124,040 
1,053 
72,770 
172 
142,160 
3,930 
74,460 
146 
Total . .507,480 6,298 
On account of the distance I had to travel I was only able to obtain 
seven discharge measurements of the Wichita river during the foregoing 
interval, but these measurements were fortunately at such stages of the 
river as to permit of a fairly good rating curve being drawn, and by 
means of this the daily discharges were obtained. 
It will be observed that while the highest monthly percentage of silt is 
over 2.75, the average for the seven months covered is only about 1.24, 
