144
LIN SHU-YEN
The admittance and drainage of water into reservoirs are controlled by movable gates fixed in the dyke. Sea-water may be allowed to remain in the reservoirs for evaporation for some time before it is conveyed into the concentrating ponds by means of an irrigation-wheel or a bamboo-bucket. When about three inches of sea-water have been bailed into the first two concentrating ponds and have been allowed to evaporate for a day or two, the brine is run into the next two ponds by gravity. One pond communicates with the other by means of a short bamboo-pipe, laid in some suitable point of the mud-ridge, to allow the water to go through, and the water from one pond can be stopped from going to the other by inserting a straw-plug into the upper end of the pipe. When the brine is sufficiently concentrated by evaporation it is finally run into the crystallization
1
2
SEA WATER RESERVOIR.
**
CRYSTALLIZATION POND
Figure 4. Diagram showing the arrangement of the different parts of a group-unit of a saline in which the ordinary solar process is employed. 1-4, concentration ponds; A, a trough, at a higher level than the reservoir, into which the sea-water from the reservoir is raised by means of an irrigation-wheel: from here it runs by gravity into number 1 pond. Pond number 1 is at a slightly higher level than number 2, which is slightly higher than number 3, which is slightly higher than number 4.