J. R. Mortimer: The Evolution of the Millstone. 97 
primitive milling, and remained the essential principle of 
every later form, down to the steel roller mill of our day. In 
most examples the grinding faces are flat; but occasionally 
the surface of the under stone is convex, and the upper one is 
concave. This form of grinding surface would greatly facilitate 
the delivery of the meal from the mill. 
Next, we have a less simple form of this mill, viz., the pot- 
quern (fig. 8), which consists of a shallow circular stone basin, 
with vertical sides internally, in which the top stone, which 
also has a hole in the centre to receive the corn, was made to 
revolve, as in the preceding example. 
In the rim of this basin-shaped lower stone is a hole through 
which the meal escapes, and falls on to whatever has been 
placed to receive it. These querns are made of almost every 
kind of stone, but in most cases the texture is well adapted 
for grinding purposes, being often of a rough, hard, and porous 
structure, 
In the earliest stages the grinding surface seems to have 
been practically effected by the porous nature of the stone, 
as no trace of tooling is observable (fig. 9). 
When the natural texture of the stone was not sufficiently 
rough for a purpose of the mealing stone, the first attempt at 
tooling the grinding surface was, as far as I can gather from 
examples discovered in East Yorkshire, to roughen the surface 
by pricking it all over with a pointed tool,* sometimes con- 
centric grooves were scratched on the grinding surface, at little 
distances apart, beginning with a small circle near the centre, 
and increasing the diameter of each succeeding circle until the 
circumference was reached. I possess the top stone of one of 
these querns (fig. 10), with its grinding face so dressed.f This 
stone has been made from a natural boulder of igneous rock, 
very little artificially shaped, except the circular grooves on 
the flat grinding surface. The two holes for handles have 
been chiselled, not drilled, and are oval in section, which is 
rather a rare feature. In most other instances these holes 
have been drilled by a tool having a rotary motion, and, conse- 
quently are circular in section. 
This particular millstone was found near Danes’ graves, 
and, very probably, belonged to the people of the early iron 
age, who lived near and interred their dead in these wrongly- 
named Danes’ graves. 
The shallow, circular grooving of the grinding surface, 
however, seems soon to have led to a more satisfactory method, 
in which we first find two circular furrows only, confined 
* A fragment of a stone so dressed is in Mr. Morfitt’s garden at Atwick. 
+ A similarly dressed millstone is in the garden at Thorpe Hall, Robin 
Hood's Bay. 
1911 Feb. 1. 
G 
