464 
How to establisli a Tile -Yard.. 
termed nubs (not stony), sliould, early in the winter, be turned 
up in beds, not exceeding in thickness from 2 to 2\ feet, to re- 
ceive the frost, which seldom penetrates to a greater depth. The 
clay thus wintered will be fit for use in the spring and summer 
following. These are found near the Dover Railway below Tun- 
bridge, in Kent ; in Hertfordshire, and elsewhere. 
Clays not adhesive, but which become so by working, are 
found in Northumberland, Warwickshire, Worcestershire, Here- 
fordshire, Derbyshire, Nottinghamshire, Leicestershire, and near 
Preston in Lancashire. They are generally of a red colour, and 
marly, full of very small stones, sometimes limewash, provincially 
termed race, and lie in beds of from 3 to 20 feet deep. They 
require to be dug in the early winter months, and I recommend 
crushing rollers to be used for the purpose of equalizing their 
texture, breaking the stones, and dissevering the race. 
This operation of crushing should be performed as the clay is 
dug, and not, as is usually the case, immediately prior to being 
converted into tiles. The advantage of this is, that labour is 
cheaper in winter ; your summer boys and men are continued in 
profitable em})loyment, an advantage obvious to every tile-maker; 
and, what is of more importance, the clay, being ground, receives 
the frost better than when thrown up in large blocks or spits. 
Practical tile-makers are aware that no clay is so fit for use imme- 
diately it has passed through the rollers as after it has lain a 
considerable time. It passes from the crushing rollers (which I 
recommend in every case to be made movable) into barrows 
placed under them, and is wheeled on to beds not more than 
3 feet thick, as near the tile-machine as possible, and, when 
watered, is left to receive the frost during the winter. I am 
aware the usual custom is to throw the clay from its beds on 
heaps 5 or 6 feet thick ; this plan is of little advantage, as the 
frost seldom penetrates more than from 18 inches to 2 feet, and 
the nubs or lumps lying below this depth, which are so detri- 
mental to the well working of tile-machines, are not softened or 
pulverized. 
It ma}- be asked hereafter why I do not recommend washing for 
this kind of clay : my answer is, that for tile-machines generally the 
stronger the clay is the belter. The last-mentioned clay would 
be weakened instead of becoming more tenacious by washing. 
Fire clay is the most difficult of all to manage, and the most 
expensive ; it is found in Staffordshire, Northumberland, South 
Wales, and in most coal-districts. Some are dissoluble with water, 
and all with frost. Its want of tenacity, unless ])roper preparation 
be used, would disqualify it for making drain-tiles by machinery. 
The first process is to grind it, either between very close-set iron 
