24 NATURAL HISTORY 
strata are shallow and lie deep, large quantities 
cannot be procured but at considerable expense. 
Among the blue rags turn up some blocks tinged 
with a stain of yellow or rust colour, which seem 
to be nearly as lasting as the blue; and every now 
and then balls of a friable substance, like rust of 
iron, called rust-balls. 
In Wolmer Forest I see but one sort of stone, 
called by the workmen sand or forest stone. ‘This 
is generally of the colour of rusty iron, and might 
probably be worked as iron ore ; it is very hard and 
heavy, of a firm, compact texture, and composed 
of a small, roundish, crystalline grit, cemented to- 
gether by a brown, terrene, ferruginous matter; 
will not cut without difficulty, nor easily strike fire 
with steel. Being often found in broad flat pieces, 
it makes good pavement for paths about houses, 
never becoming slippery in frost or rain; is excel. 
lent for dry walls, and is sometimes used in build. 
ings. In many parts of that waste it lies scatter. 
ed on the surface of the ground; but it is dug on 
Weaver’s Down, a vast hill on the eastern verge 
of that forest, where the pits are shallow and the 
stratum thin. This stone is imperishable. 
From a notion of rendering their work the more 
elegant and giving it a finish, masons chip this 
stone into small fragments about the size of the 
head of a large nail, and then stick the pieces into 
the wet mortar along the joints of their freestone 
walls. This embellishment carries an odd appear. — 
ance, and has occasioned strangers sometimes to 
ask us pleasantly “whether we fastened our walls 
together with tenpenny nails.” ' 
