lO 
NATURAL HISTORY 
with a {lain yellow or rujl colour, which feem to be nearly as laft- 
ing as the blue; and every now and then balls of a friable fub- 
fbance, like ruft of iron, called ruJl balls. 
In IVolmer Foreji I fee but one fort of ftone, called by the work- 
men /and, or forejl-jlone. This is generally of the colour of rufty 
iron, and might probably be worked as iron ore; is very hard and 
heavy, and of a firm, compact texture, and compofed of a fmall 
roundifh cryflalline grit, cemented together by a brown, terrene,, 
fermginous matter; will not cut without difficulty, nor eaiily ftrike 
fire with fteel. Being often found in broad flat pieces, it makes 
good pavement for paths about houfes, never becoming flippery 
in froft or rain-, is excellent for dry walls, and is fometimes ufed 
in buildings. In many parts of that wafte it lies fcattered on the 
furface of the ground; but is dug on Weaver's Dozvn, a vaft hill 
on the eafhern verge of that foreft, where the pits are fliallow, and 
the ftratum thin. This flone is imperifliable. 
From a notion of rendering their work the more elegant, and 
giving it a finilh, mafons chip this ftone into fmall fragments about 
the fize of the head of a large nail ; and then fhick the pieces into 
the wet mortar along the joints of their freeftone v/alls : this em- 
bellifhment carries an odd appearance, and has occafioned ftrangers 
fometimes to afk us pleafantly, " whether we fattened our walls 
together with tenpenny nails." 
LETTER 
