20 
LOSSES FROM CANALS BY SEEPAGE. 
cost, of $400,000.* The loss under these favorable circum- 
stances still amounts to about 5 inches in depth per day. 
Where the Cavour canal crossed the valley of the Dora 
river it was confined by artificial banks and the losses at 
first were found to be enormous, being not less than 210 cii. 
ft. per sec. in a distance of but little over one mile.f d'his 
corresponds to a depth of 20 feet per day over the entire 
width of the canal. 
This great loss was remedied by using sand in the bot- 
tom, using water made muddy with clay, and lime water, 
and after repeating the application several times the losses 
were found to be much less. After continuing the applica- 
tion for a couple of months, keeping the water stagnant to 
allow the material to settle, the losses were very much re- 
duced. 
CONTINUOUS RECORDS. 
For two years a self recording nilometer was maintained 
on a ditch four miles long, belonging to the North Poudre 
Land and Canal company. The lateral had no outlets for 
that distance. Weirs were placed at the upper end near 
the reservoir from which the water was drawn, and also 
near the lower end about four miles from the reservoir. No 
water was used at intermediate places. dTe record was- 
made to ascertain the loss there might be from seepage and 
evaporation during the time. The lateral is built in a soil 
mostly of clay, which does not wash unless the velocity is 
considerable. The seepage was not expected to be great 
because of the character of the soil. Two weirs were put in 
place and instruments were put in place at the side of the 
ditch, with floats so arranged that as the water rose or 
fell a pen rose or fell on the paper correspondingly. The 
clockworks would run a week without rewinding. At the 
end of each week the instruments were visited, the clock re- 
wound, the papers changed, and check readings of the 
height of water over the weirs taken. 
After the instruments were in service it was found that 
about ten acres of ground was supplied from the lateral 
above the lower weir. The cases when water was drawn 
for this tract are eliminated from the table, but the condi- 
tions were not entirely satisfactory, and, as the funds to 
meet the small expense of removing the weir above this lat- 
eral were not available for the department at that time, the 
measurement was dropped. A ditch in the southern part 
* Salvador, llydraulique .Agricole. 2:42. 
t IlerrisBon, Ues Irrigations de la Vallee dn Po. p. 77. 
