244 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



bottom. Is this necessary for a perfct cistern ? In sinking one I 

 shoukl strike coarse gravel about a foot from the surface. Were 

 I to plaster it with plastic slate, would it need as thick and care- 

 fully built wall as if cemented ? 



What is the best shape for one 14 feet deep, with an average 

 diameter of five or six feet, considering that I am no mason myself 

 and can get but poor workmen here ? About how much cement 

 or plaster will it take for a cistern of the above size, and how 

 many brick for filtering partition to come to the top ? I ask 

 because all these I must freight from St. Louis at considerable 

 cost, and have only a few opportunities in a year to get them at all. 



Mr. Solon Robinson. — Cement, to be good and water-tight, must 

 be mixed with as much water as it can be worked with. The sand 

 must also be coarse and sharp. It is not necessary to build a thick 

 concrete wall, nor any other wall. We have a good cistern plas- 

 tered directly upon the earth. It is circular, the bottom dish- 

 shaped, seventy-three feet deep, seven feet wide. Took three 

 barrels of cement. If the gravel stands firm, you can plaster it. 

 If not, make a concrete or brick-wall, barely thick enough to 

 stand. Plaster it with water-lime or plastic slate; but mind you, 

 not such plastic slate as is used for roofing. The coal tar for roofe 

 7nust not be cooked; the tar for cisterns must be boiled until the 

 joitch when cold is as brittle as glass. Then melt and add the 

 slate flour until stifi" enough to be used with a trowel. A cistern 

 plastered with this will be tight and endure forever. The coat 

 need not be over a quarter of an inch thick. Your leaky cisterns 

 can be made tight in the same way. Probably a coat put on with 

 a brush would do it. As slate mastic is a patented article, you 

 cannot use it without license. Any Yankee who writes as you do 

 can build a cistern. I would rather hire you at a venture than 

 half who pretend to be masons. If you cannot get cement, build 

 a cistern of wood. We built one twenty-five years ago, which 

 still holds water. Staves made of pine plank jointed together, 

 a bottom of the same, and hooped just enough to hold together, 

 is all that is necessary. The bottom of the hole was then puddled 

 with clay. Upon this soft bed the big tub was dropped. Claj'- 

 was tamped around the sides, holding the staves as tightly together 

 as though iron-hooped. Joyce's pump is good, but we prefer 

 West's. Freezing does not kill it. 



