312 THE FARMERY. [Chap. III. 



'■ "Win'n you get witJiin about two feet of the top, commence gradually to 

 draw in llic work toward the center, leaving, when liuishcd, a space open 

 al.'out two feet across. The next tiling is to plaster the inside with cement ; 

 a!.-i> the top on the outside, commencing where you began to draw in. About 

 two courses of brick are laid round the mouth of the cistern, forming a neck, 

 wiiicli adds to the strength of the top. Kow cover the whole with earth, 

 except the neck. The water is conducted to my cistern through a small 

 brick drain laid in cement. I also have a drain near the top to let oft" the 

 surplus water. If a cistern is made out of doors, it must be below the reach 

 of frost. Lead pipe would probably be cheaper than brick to conduct water 

 to and from tlie cistern. 



'• I have no doubt but that a cistern made this way of hard Ijrick would 

 last a century. Mine, holding 1,000 gallons, cost $18. The larger the size, 

 the less tlic cost in proportion to the capacity. If the earth is lirni and hard, 

 you may lay the brick close against it, thus saving the trouble of iiiling in 

 and digging so large. I have known tiiem made by cementing directly on 

 the earth, using no brick, and covering the top with timbers or plank. One 

 made with brick will cost more, but I think it best and cheapest, taking into 

 consideration safety and durability." 



Tables of Contents of CmcuLAR Cisterns. — The following tables of the 



size and contents of circular cisterns may be convenient to those about to 



build them. For each foot of depth, tlie number of barrels answering to 



the different diameters is as follows : 



Fur 5 feet in diameter 4.G6 barrels. 



C " " 6.71 



7 " " 9.13 



8 " " 11.93 



9 " " 15.10 



10 " " 18.65 " 



A cistern Zl feet diameter will hold for every 10 inches iu depth 59 gallons. 



4' " " 78 



i\ " " 99 



" 5 " " 122 " 



51 " " 148 " 



G" " " 176 



8 " " 310 " 



You will find \>y this table that a cistern six feet deep and six in diameter 

 will hold 1,260 gallons, and each foot you add in depth will liold 210 

 gallons. Tlierefore, one ten feet deep and six in diameter will contain 

 2,100 gallons. 



To find the contents of any cistern in wine gallons, the diameter and 

 depth being known : 



1. Multiply one half the diameter (in feet) by itself. 



2. Multiply tlie above product by 34, which will give the area of the bot- 

 tom of the cistern nearly. 



3. Multiply this by the number of feet in depth ; this will give the cubic 

 contents in feet. 



4. ]\Iultipl3' the last product by 1,728 (the number of cubic inches in a 

 foot), which gives the number of cubic inches. 



