RESERVOIR BUILDING. 59 



embankment. A three-inch discharge pipe was laid at the 

 bottom, with necessary fittings. 



"The reservoir is nearly seven feet deep when filled, 

 and forms an excellent bathing tank for the family in 

 addition to its irrigation service." 



This is a very thorough style of construction. It would 

 be cheaper to excavate as described in the previous list 

 of suggestions and then trust to a clay layer evenly spread 

 over the bottom and sloping sides, but the use of the pud- 

 dle trench and flat floor is surer to hold water. The puddle 

 trench is carried to the top of the bank : clay layering on 

 the sloping bank will crack as the water is drawn down 

 and is apt to be leaky. Mr. Berwick has scraped out a 

 very rich deposit of mud and decayed leaves and water 

 weed once since he built the reservoir, thus obtaining a 

 considerable amount of fertilizer, and after scraping, the 

 bottom was given a new floor of clay. He has also raised 

 the sides of the reservoir one foot and put in exit pipes of 

 four and six inches to release water in different directions. 



Stone or Brick Walls for Reservoirs. Very shapely but 

 rather more expensive walls can of course be made of 

 stone or brick laid in cement, and in this way the water 

 contents of the same diameter can be increased. The bot- 

 tom can be puddled or clayed or cemented, according to 

 the character of the ground or the taste of the builder. 



Subterranean Reservoirs. Large shallow wells are often 

 the cheapest reservoirs, and with pumps of large outflow 

 sufficient head is secured for direct application to the dis- 

 tributing ditches. Tunnels are also subterranean reser- 

 voirs and are frequently used as such. Both these wells 

 and tunnels are economical of water, as evaporation is 

 very slight. The following is an instance : 



"Mr. C. L. Durban says that the cheapest reservoir that 

 a man can build on his land for retaining water for irri- 

 gation purposes is a tunnel run into a hill. An open res- 

 ervoir in a canon or other suitable place, will lose one-third 

 of its water during the summer from evaporation, while 



