HEATING BY HOT WATER. 203 
the house at some convenient point—usually at one end— 
and fed from outside. The body of the furnace, which 
of course projects inside the house, and should be 
placed so low down as to only rest on the ground 
level, or be partially sunk im the floor, must be subs 
stantially constructed of fire-brick and tiles, put together 
with fire-clay rather than mortar. From it the flue 
is taken, usually Slong the front of the house, to a 
chimney built just outside at the farther end. The usual 
size (internally) of a brick flue is Qin. by 9in., and it is 
generally constructed 
by laying three courses 
of a single brick on L 
the flat (4}in. work), a eel ae 
or two courses of a = a eae ae y 
brick on edge, which !— a j le 
of course comes to hithys Uj 
the same thing, for Myre a 
each wall, or side. Fig. 141. 
Between these a 
space of Qin. is left, and the whole, when finished, is 
covered in with the flat square tiles, 14in. or 2in. in 
thickness, known as ‘‘quarries.” These are made in 
both red and blue material (the former being the most 
suitable for this purpose), and are 6in., 9in., and 12in. 
square, the last size covering a Qin. flue nicely, with 1din. 
lap on each side. 
The tiles must be very well and carefully bedded in 
and jointed with the best mortar, and indeed the whole 
of the work must be made as sound and tight as possible. 
Fire-tiles ought to be used over the fire, and for a few 
