STAGING, BEDS, ETC. 109 
The best description of paving material for the walks 
of conservatories, corridors, and the like, is the flat, square 
Staffordshire tiles known as quarries, which are made in 
several sizes, and from 4in. to 12in. square. These are 
made in black or dark blue, red, and buff, and if a good 
quality of tile is used and neatly laid on a concrete bed, 
with cement, a very nice effect is produced by setting them 
alternately in two or three colours. 
Concrete, formed of Portland cement and coarse or fine 
gravel, is probably the next best material. Concrete may 
also be made with hard burnt ‘ballast ” (burnt clay), and 
even coal ashes and coke are sometimes employed, though 
none of these wear like 
gravel. Asphalte or tar 
paving is hardly suitable, 
owing to the quantity of 
tar employed, but good 
concrete makes a firm, 
clean, and perfectly sweet 
path or floor, easily swept or washed down at any time, 
and almost everlasting. Flag stones of almost any kind 
or size may of course be employed, if convenient, but 
these are usually somewhat costly. 
In conservatories and other large structures the heating 
pipes are frequently placed in trenches sunk beneath the 
floor or pathways, and when this is done a continuous 
grating of some kind must be employed (see Fig. 72). 
This method of heating, though rendering the somewhat 
unsightly pipes invisible, is on the whole not to be 
recommended, for reasons which will appear presently, 
but where adopted the light cast-iron gratings usually 
