into an engine-room 50 by 50 ft., and a boiler-room 50
by 30 ft. A concrete coal-bin adjoins the exterior boiler-room door.
Coal is delivered directly from the car to the bin.

The plant is lighted by a small, but very complete, engine and dynamo on
one base and run by steam from the Sterling boilers.

The two plants are exactly alike throughout.

_Reservoir Leakage_.--The Nogal Reservoir basin is covered with from 2
to 5 ft. of good clay, except where it is punctured by a dike, or washed
down to the underlying sandstone by a few gullies. These punctures or
washes were covered or filled with clay from 1 to 4 ft. deep. During the
first season the leakage, above the 6-ft. contour, was at the rate of 2
in. per day.

As the water fell, due to leakage, evaporation, and use, a herd of from
300 to 400 cattle were worked around the shore line. This reduced the
leakage to 3/8 in. below 8 ft., and to nothing below 6 ft., above the
outlet. As the flow line rises higher each season, the puddling will be
continued to the top. The leakage at 12 ft. above the outlet, or 17 ft.
above the bottom, is still approximately 1 in. per day. The total
puddling, to date, covering two seasons, is equivalent to 11,150 days'
work of one cow, and covers an area of 1,500,000 sq. ft.

The clay packed densely, the final hoof marks being not more than 1/4
in. deep and remaining distinct under the water around the shore line
for one year. Apparently, the reservoir will finally become water-tight
at all elevations.

The soil in which the four service reservoirs on the railway are built
proved to be about the worst for such work. In its natural state on the
prairie, after the excavation for the reservoir was completed, it
filtered water at the rate of 3 ft. per day. Tamping and puddling still
left a filtration of 12 in. per day, with a tendency to increase. Enough
water filtered through the concrete to produce settlement and cracks.
Finally, the concrete was water-proofed with two coats of soap, two of
alum, and one of asphalt. This has made all the reservoirs water-tight.
Elaterite, an asphalt paint made by the Elaterite Paint and
Manufacturing Company, of Des Moines, Iowa, was used successfully on the
Luna Reservoir. This paint is applied cold, and preliminary tests showed
it to be quite efficient.

The analysis of the soil is as follows:

Loss on ignition 3.35
Silica 56.36
Oxide of iron