HEATING BY HOT WATER, 915 
or open-work iron are frequently employed to hide the 
unsightly pipes, etc. 
Stoke-Holes.—As it has been already shown that 
in order to work well all boilers should be set well down 
below the level of the pipes, it follows that they must 
generally be sunk in the ground to some extent, and the 
larger the boiler the deeper must the stoke-hole be. 
Several forms of boilers that require a comparatively 
shallow hole have already been described (see pp. 187 and 
189), and one or other of these ought, 
to be adopted wherever any difficulty rae 
is experienced, or anticipated, in 
getting a sufficiently deep stoke-hole : | 
for the usual types. The obstacle 
chiefly met with in such work is | 
water, and if this is found at a less 
depth than that necessary to get the 
boiler in properly the construction 
of the stoke-hole will be unavoidably 
rendered more troublesome and 
expensive—that is, unless it can be 
easily drained into some neighbouring deep sewer or 
outfall, when the difficulty of course disappears. 
But where water is met with inconveniently near the 
surface, and cannot be got rid of, ii must be kept out by 
some means, and in fact a kind of water-tight tank be 
constructed, but to keep the water ouwé instead of in—~a 
decidedly more difficult task, though by no means an 
impossible one. 
One way out of the difficulty is, after having taken out 
a hole of the proper size and depth (the water being kept 
Fig. 159. 
