Farms and Villages. 
35 
The roofs, we have seen, will yield a little more than the 
:above minimum requirements. 
In this case a storage-tank of iron, or even of masonry, would 
prove very expensive, consequently a pond or open earthwork 
reservoir (Fig. 1) would have to be provided. If the ground 
happen to slope up, so as to allow of a pond being dug in the 
ground at a somewhat higher level than the floors of the build- 
ings, the cheapest and most convenient arrangement possible 
will result. If the ground be impervious to water, it will be 
only necessary to dig a hole 55 feet square at the surface, by 
6 feet deep, with the sides sloping li horizontally to 1 vertically. 
If the ground be porous, the pond will have to be lined with 
puddle — that is good stiff clay worked into a plastic mass and 
'laid from 6 inches to 9 inches thick all over the bottom and 
sides — and the latter, at any rate, should be protected by paving 
of some kind over the puddle ; brick on flat will do, but concrete 
in cement about 4 inches thick will answer equally well. Con- 
crete alone, however thick, will not make a water-tight basin, 
even when it is quite free from cracks (which is rarely the case) 
and rich in cement, whereas puddle never cracks, and remains 
absolutely tight as long as it is undisturbed. If the puddle be 
protected in either of the ways mentioned, its thickness may be 
reduced to 6 inches. Should there be no high ground available, 
the pond can be made on the surface by an embankment about 
() feet high, enclosing the required area, as shown in Fig. 1. 
The crest should be about 3 feet wide, and the banks sloped 
inside and out 1^ to 1. The inside must be lined with puddle 
and concrete, or brick, in the manner described above. The 
cost of a plain pond will be about 16Z. ; of one lined with puddle 
and concrete, 46?. ; and one made on the surface, 65/. A low, 
but close fence should be placed round the reservoir to prevent 
animals getting access to it. 
The diameter of the main-pipe bringing the water to the reser- 
voir must be calculated on the assumption that 1 inch of rain may 
fall in an hour ; this over the area of roofs will give a rush of ~~ 
50 cubic feet per minute ; and, assuming a maximum velocity in 
the pipe of 6 feet a second, or 360 feet per minute, the area of 
50 c ft 
the pipe will be = — = 'IS? square feet, which corre- 
^ ^ 360 feet ^ 
sponds to a 5-inch pipe. If the reservoir be on a higher level 
than the ground this pipe will be under pressure, and should be 
of cast-iron with properly made lead or rust joints. The down 
pipes from the eaves-gutters should be carried as much as 
possible on a level higher than the reservoir, so as to avoid 
having more of the expensive underground pipe than is 
absolutely necessary. 
D 2 
