and China-clay of Cornwall. ~ 55 
rally from 20 to 40 feet square, and 2 deep; the pans, when 
two-thirds filled with clay, are thus exposed to the heat of 
the sun, or the dry winds of March, to the aid of which alone 
the proprietors of the majority of these works have hitherto 
had recourse. 
In the model which I have sent for the inspection of the 
Committee of the Royal Cornwall Polytechnic Society, I have 
employed drainage as an additional means of aiding the dry- 
ing of clay, by forming a kind of filter of the clay pan. A 
substratum of large pebbles, increasing in depth from behind 
forwards, but with the surface level, is first laid down above 
this coarse gravel, between which and the clay to be dried is 
a thin layer of fine sand ; through this the water quickly runs 
to the corner, towards which the inclined bottom is made to 
fleet, which communicates with the country by means of a 
launder, over the inner end of which is placed a wire-gauze 
grating. By the employment of these, from experiments I 
have made, I have ascertained that the clay can be dried 
thrice as rapidly as by the ordinary methods ; in addition to 
the introduction of which I should recommend to the notice 
of parties employed in these operations, the propriety of 
placing these pans as closely together as possible, so that, on 
the occurrence of heavy showers of long duration, or in the 
heavy dews of the nights of summer, the clay may be kept 
from this accession of moisture by some cheap covering, as 
these obstacles very much increase the difficulty of drying 
clay in any given period. 
The kaolin is by this means only partially deprived of mois- 
ture, in order to effect the complete removal of which it is 
taken from the pans, where it has been allowed to remain for 
from three to four months, to the drying grounds, on the ad- 
joining hills, in summer, in cubic blocks about 1 foot square. 
In order to effect its removal from the pans, a number of 
parallel incisions are made the whole length of the pan, in 
one direction, by means of a perpendicular knife attached at 
right angles to a long handle. These long blocks are then 
divided transversely by men, who with spades throw them 
on a board, on which they are carried by women and boys to 
the sandy drying-yard, where they soon become perfectly dry 
