156 
FLORIDA STATF GEOLOGICAL SURVEY. 
“In both these tables it has not been thougnt necessary to 
make any allowance for the resistance of the atmosphere. Doubt¬ 
less, when the velocity of the stream is great, the resistance is 
considerable; but as the pressure checks the flow, and our object 
is simply to measure the amount of flow, it need not be taken 
into consideration. In case pipes are found of diameters not: 
corresponding to the table, the same rule may be applied as in 
the first case. 
“Whenever fractions occur in the height or horizontal distance 
of the stream, the number of gallons may be obtained by dividing' 
the difference between the readings in the table for the nearest 
whole numbers, according to the size of the fraction. For 
example, if the distance from the top of the pipe to the top of 
the stream, in the first case, is nine and one-third inches, one-third 
of the difference between the readings in the table for nine and 
ten inches must be added to the former to give the right result. 
In case one measures the flow of his well according to both 
methods, he may think that they should correspond, but such is. 
not' the case. In the vertical discharge, as there is less friction, 
the flow will be larger, so also difference will be found according 
to the length of horizontal pipe used in the second case. The 
longer the pipe, the more friction and less the flow. 
“As pipes are occasionally at an angle, it is well to know that 
the second method may be applied to them, if the first measure¬ 
ment is taken strictly vertically from the center of the opening, 
and the second from that point parallel with the axis of the pipe 
to the center of the stream as before. The measurements may 
then be read from the table as before. 
“This method is also applicable to measuring the discharges., 
of different pipes when water is distributed about a farm or in 
a city. 
“Pipes which have been cut in the usual way are frequently 
diminished in diameter by the incurving of the edge of the pipe. 
This will diminish the flow, but how much can only be roughly 
estimated. It will be greater than that of a straight pipe having; 
the exact diameter of the opening as reduced.” 
