290 Transactions of the American Institute. 



September 5, 1871. 



Nathan C. Ely, Esq., in the chair; Mr. John W. Chambers, Secretary. 

 A Self-filtering Cistekn. 



Mr. William Dyer, of Ashland, Schuylkill county, Pa., " wished 

 to know the best plan for making a self-filtering cistern for domestic 

 use, to receive water from a slate roof twenty by forty feet. "What 

 size cistern is best ? . And most especially do I wish to know how to 

 make the filtering arrangement." 



The Chairman — The size of a cistern must depend very much on 

 the size of the family for which it is intended. Some of our friends 

 have many children, and others have no family save themselves. Mr. 

 Lyman has an extensive household, and can, perhaps, throw some 

 light on this subject. 



Mr. J. B. Lyman — I have built a circular cistern, the walls con- 

 verging toward the bottom like an inverted cone. The sides are 

 cemented by placing the cement directly on the gravel. In the mid- 

 dle of the bottom, which is of brick, there is a square filter sunk 

 below the level of the cistern-bottom two feet, being four feet wide, 

 to serve as a filter. This filter is divided by a brick wall, made with 

 very little mortar, so that the water easily passes through it. Above 

 this filter division rises a wall of brick to the top, completely divid- 

 ing the cistern in two. The filter is filled with fine charcoal and 

 gravel, about half a hogshead of this mixture being used in the filter. 

 Over this mixture about three bushels of pebbles are placed to keep 

 the charcoal and gravel in their place. The water enters on one side 

 of the wall, passes down through the charcoal and gravel, percolates 

 through the unmortared brick wall, and comes up on the other side 

 free from impurities, whence it may be pumped out and drank. 

 When these cisterns are new there is a slight lime taste about them 

 from the mortar, but that soon passes off, not being noticeable the 

 second season. This cistern is built after a plan furnished me by 

 the late Professor Mapes. 



Dr. Isaac P. Trimble — Last week I talked with a gentleman who 

 uses cistern water exclusively, and his plan of filtering it is much such 

 as has been described. 



Mr. Thomas Cavanagh — It would be better to have the filter on one 

 side,, near the top, where it could be cleaned more readily when foul. 



Dr. J. V. C. Smith — In the city of New Orleans they use cistern 

 water, which is collected in huge tanks. They use no filters. The 

 sediment collects at the bottom of them. 



