lilamcrc Tanks 



[6i 



be 4}4 lb. nearly, and this would be exerted 

 on every square inch on the bottom, or the 

 whole pressure on the bottom would be 

 625 lb., the weight of 10 cubic feet of water. 

 Keeping this in view, it will be seen that 

 length and breadth produce no effect on 

 the pressures that a fluid exerts against the 

 vessel or body that retains it ; and that in 

 calculating the resistance to sustain such 

 pressure, depth is the only element requiring 

 to be taken into account. It is also to be 

 kept in view that pressures on the bottom or 

 sides is directly as the depth ; thus, if our 

 supposed cistern were reduced to 5 feet in 

 depth, the pressure on the bottom would only 

 be one-half, or 2^ lb. on each square inch." 

 Keeping these principles in view, a tank, 

 therefore, should not exceed six feet in depth. 

 Its length being immaterial, so far as its con- 

 struction is concerned must depend on the 

 size of the farm, or rather on the number of 

 cattle housed upon it. A convenient width is 

 six feet, for this admits of an arch being car- 

 ried over the tank at a moderate cost. As a 

 rough guide to the size of tank required on a 

 farm, an allowance of 1000 gallons for each 

 €Ow f should be made ; and this number of 

 gallons occupies 162 cubic feet. 



In fixing a site for a tank, the north side of 

 the steading should be chosen ; but where this 

 is not practicable, a sheltered situation in any 

 other part must be selected. No matter what 

 the character of the soil, no tank can be pro- 

 perly constructed without puddling, by which 

 means alone the ingress of drainage-water and 

 the egress of the urine is prevented. The 

 excavation should be carried at least 18 

 inches deeper than the proposed tank, and 

 any water standing in the excavation must be 

 drained off before laying in the prepared clay, 

 Avhich must be neither too wet nor too dry, 

 but in a condition to combine with solidity. 

 It should not be thrown in at once and 

 beaten down ; but one layer after another 

 should be spread till the whole reaches 15 

 inches in thickness ; and upon this the walls 

 should be built with brick, not less than 9 

 inches thick, the back of the wall being firmly 

 puddled as the work proceeds. The bottom 

 t)f the tank may be either laid with pavement 



VOL. I. 



or brick on edge, the level falling towards the 

 centre, where a well-hole of about a foot in 

 depth, should be provided to receive the end 

 of the suction-pipe. The bricks should be 

 laid with mortar, and Avhen the tank is com- 

 pletely built, all the joints should be picked out 

 and carefully pointed with Roman or Portland 

 cement. A very useful addition to all manure 

 tanks is an " agitator," to be used to stir the 

 liquid when water is added, so as to bring the 

 contents to auniform state when being drawn off. 

 This agitator, which is shewn in Fig. i {a), con- 

 sists of an iron rod, with two or four arms or fans 

 working in a socket fixed in the grating over 

 the well-hole. The rod is brought through 

 the cover of the tank about 3 feet, and termi- 

 nates in two handles at right angles to the 

 rod, by which the agitator is set in motion as 

 required. Fig. i shews the section of a tank 



(i=^ 



iX 



constructed in the manner thus described, a 

 being the agitator ; b man-hole ; c pump, with 

 moveable hose or fixed piping liquid for filling 

 the manure cart. 



The mode of constructing the Flemish 

 manure-tanks, alluded to above, is thus de- 

 scribed by Mr Stephens : — 



" The tank is frequently constructed under- 

 neath the stable and cattle-house, the liquid 

 being led to it by open gutters running along 



M 



