9 
early water rights may appear to use large quantities of water and 
thus have small duties. But they will all the more likely represent 
the practice where there is water accessible whenever needed. 
The water applied to the individual fields was measured over a 
weir of the trapezoidal pattern, due to Cippoletti of Milan, as de¬ 
scribed in Bulletin No. 13. This form of weir was adopted because of 
the greater ease in reducing the measures. The maps of the various 
fields show the location of the weirs which were arranged to fulfill 
the conditions as described in the bulletin mentioned. In one, that 
of Mr. McClelland, the crest which was originally 30 inches, was 
found to be too small for the convenience of the irrigator, and was 
lengthened to three feet, without, however, widening the box in which 
it was placed. This would have the effect of slightly lessening tho 
lateral contraction and thus increasing the discharge, but as the 
error due to this is small, it has not been taken into account in 
the reduction, as necessary errors do not warrant this degree of re¬ 
finement. 
The instrument for recording the depth of water on the weir 
w'as of a pattern made by Richards Bros., of Paris. At one side of 
the box and above the weir a well for the float to move in w^as made 
and connected with still water above the weir. This float rose and fell 
with the water in the ditch, and was connected with a pen which re¬ 
corded on a cylinder moved by clockwork the change in the height 
of water. A copper wire served as the connecting cord between the 
float and the pen. The first clockworks sent by the manufacturers- 
revolved daily, but as this was inconvenient for our purposes weekly 
movements were afterwards substituted. When the papers were 
changed, as they were weekly, the height of water w^as measured 
and recorded as a check upon the instrument. Only once or twice 
was there any reason to suspect a slipping of the wire over the pulley 
connecting with the clockwork. 
In the case of the river and the canals it was impracticable to* 
measure the water over weirs, but each canal is provided with a 
rating flume some distance below the headgate, which is officially 
rated by the State Engineer, and is the basis for the distribution of 
water to the ditch. The instruments were so placed as to record the 
depths in these flumes. In the case of the river, the water district 
has provided a gauging station where all ratings are made, and 
sufficient have been made during the past years at different stages 
of water to give the quantity of water flowing at any given depth 
with a fair degree of accuracy. 
From the sheets from the recording instrument the depths 
acre found, reduced to cubic feet per second, and multiplied by the 
number of seconds during which the height could be considered! 
constant. When the height was varying, this time was short.. 
Each day was added separately. 
The reductions themselves have been made almost entirely by" 
Mr. R. E. Trimble, assistant in this section of the Experiment Station.. 
