CISTERNS AND TANKS. 



33 



A mill with arms six feet long may be made to do work 

 equal to one-fourth of a horse-power, if all the working 

 parts are well fitted and kept well lubricated, as all 

 machinery should be. When out of use, the sails are un- 

 tied and removed, or they may be furled and clewed to 

 the arms until again required. 



A one-horse railroad-power would also serve a useful 

 purpose in raising water from wells into an elevated res- 

 ervoir, where it could be stored for use. For small 



Fig. 2. SQUARE TANK. 



gardens the water from the roofs of buildings may be 

 collected in tanks or cisterns raised a few feet above the 

 level of the ground. 



A round tank, hooped with iron bands, 12 feet deep 

 and 15 feet in diameter, will hold over -15,000 gallons. A 

 square tank (fig. 2) may be made of jointed and matched 

 planks, which are forced closely together by wedges, act- 

 ing upon a timber frame which encloses the planks. This 



