96 ANNUAL REPORT 
saving an immense quantity of water from loss by percolation and from 
being taken up by useless vegetation along the line of the ditch. They 
prevent burrowing animals from destroying the ditch banks. They allow 
much flatter grades in the ditches, thus permitting larger territories to be 
brought within the irrigation sphere. As the surrounding ditch banks 
are not saturated, weeds do not grow,along the canals to any great extent, 
therefore the farmer is not so seriously troubled with weed seeds being 
distributed over his farm in such immense quantities as formerly by the old 
open earth ditches. Within his farm limits the ditch presents a more pleas- 
ing appearance than the old weed bound ditch. It saves annually upon the 
cost of cleaning and repairing, which was originally required. Thus 
cement is a great boon to the western irrigator. 
RESERVOIRS. 
Mr. John Randall, of San Francisco, Cal., said he had coated a 
reservoir (in 1889) with a 1% inch coat of cement mortar upon the 
original sand and gravel surface. The,mortar used was a I to 5 Portland 
cement mortar put on in one layer while the sand surface was moist. 
This structure had held water for four years against a head of 16 feet. 
without leaking. i 
In the water supply system for Aurora, Ill., there is a reservoir 
150 by 140 feet in area, and 12 feet deep excavated through a layer 
of gravel and into a stratum of shattered limestone. This reservoir is 
lined with concrete 8 inches thick, except above the rock where the lining 
becomes a wall, reinforced at frequent intervals by heavy concrete but- 
tresses about 5% feet thick at the base just above the rock. The concrete 
used was I part cement, 2 parts sand and 3 parts stone in the lining, and 
I part cement, 3 parts sand, 6 parts stone in the heavier masonry. 
This reservoir is illustrated in figure 4o. 
CISTERNS. 
In 1876, the writer assisted his father in constructing a cistern in 
Pomona, Cal:, which was lined with Portland cement mortar. The 
cistern was 7 feet in diameter and 11 feet deep, dug in a gravelly, loamy 
soil, and into a substratum of nearly pure sand and gravel. It was 
eventually coated with three coats of plaster. The plaster was composed 
of an imported Portland cement and sand. The proportions are not 
definitely remembered, but were probably about I cement to 3 sand. The 
first coat was plastered directly upon the clean cut gravel walls in a coat 
about 34 inch thick. The second coat, about 4 inch to 3% inch thick, 
was plastered over the bottom and upon the sides to within about 4 feet 
of the top of the cistern. ‘The interior surface was then washed with a 
neat cement cream. Water was turned in and entirely disappeared in 
twenty-four hours. Upon examination it was found that the weight of 
