It was constructed of dry stone, grass, and earth, with the addition
of strong wood-work. The rocks upon which it had to be built were full of
fissures, and when it was desired to close it great leakages of water
occurred, which came near ruining it and necessitated the construction of
a second wall behind it and a talus of earth in front. The dam as shown in
Fig. 1, when finished, had a thickness of 25 meters at the base. It was
closed on the second of July, and had a storage capacity of 55,000 cubic
meters.
The principal excavation was begun at the point where the bed was deepest,
and which consequently the older miners must have had most trouble in
reaching. Here were set up two Letestu pumps that were actuated by a
four-horse wheel.
These pumps lifted 50 cubic meters per hour. All except the pump chambers
and pipes was made of wood on the spot. The water that was lifted was
carried away from the works in a flume 160 meters in length, which
likewise removed the water from the motive wheels.
For the service of the same excavation two simple acting inclined planes
were installed that were moved by a four-horse wheel. Fig. 2 gives a
general view of the arrangement.
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