STAGING, BEDS, ETC. 97 
These may be constructed of considerable size, and hold a 
lot of water, but they are by no means sightly objects, 
and are, on the whole, more suitable for use outside than 
under glass. 
But in most cases, and for all ordinary purposes, there 
is nothing to equal a tank constructed of good sound 
brickwork, and well lined with fresh Portland cement. 
These may be made of any size or form, are practically 
imperishable, very strong, and comparatively inexpensive 
as well. They are usually, at any rate partly sunk in 
the ground, and may be built entirely below the surface 
if desired, in which case the work need not he quite so 
stout or strong as if constructed entirely above ground. 
Indeed, underground tanks or cisterns may be and 
frequently are constructed entirely of concrete, made of 
coarse gravel, burnt ‘‘ ballast,” or the lke, and faced with 
a good coat of cement and sand only. 
Nine-inch work, especially if put together with good 
mortar, to which a little cement is added just before use, 
and all the bricks soaked or wetted, will be found 
sufficiently substantial for all but very large cisterns, in 
which fourteen-inch work should be used. If formed of 
concrete the sides should be from 10in. to 12in. or 1din. 
in thickness, and have a good thick coat of cement put 
on inside as well. A concrete bottom is frequently 
employed, even for brick tanks, putting down a quantity 
of rough or broken bricks, etc., first, these being well 
* srouted’”’ in with plenty of thin lime-mortar, and when 
set, covered with a coat of fine gravel-concrete, mixed 
with a little cement, and finally coated with cement and 
sand only. A layer or course of bricks laid on the flat, 
H 
