•J 
289 MINKI, METALS, AKB GEMS. 
celebrated during several centuries for its t, 
trade in coals. It was first made a borough by ci'.| 
and the earliest charter for 
f 
Conqueror, and the earliest charter for 
granted to the inhabitants, was in tlie reign .of f 
in 1239 ; but in I30C), the use of coal for a'rbf’ 
liibited in London , by Royal proclamation, 
iiiuiLcu u» i^onaoi], uy xvoyai proLi<im:ui.uii, 
it injured the sale of wood, with M'hich the ^ 
This interdict 
bf V 
the Capital were then overspread. 
however, continue long in force ; and coals 
sidered as having been dug for exportation at N®' 
more than four centuries. It ha.s been estimatet* j 
are twenty- four considerable collieries lying at diff 
tances from the river, from five to eighteen miles > , 
they produced, or an average of six years, cl 
close of 177b, an annual consumption of tlttc® ^ 
and eighty thousand chaldrons, Newcastle teefsc 
to .seven hundred and seventeen thousand, , yh 
fifteen chaldron.s, London measure) of {iP 
thirty thousand chaldrons were exported c!^ 
parts. The boats employed in the colliery 
keels, and are described as strong 
each carrying about twenty tons and of 
dred and fifty are kept constantly employed 
clumsy, 
these 
1776 an estimate was made of the shipping 
■; and from this estimate it af|l! .^ * j 
three thousand, five hundmd, and eighty- fire “ 
- - 
during that year engaged in the coasting 1,|^ 
hundred and sixty-threo in the trade to foreign 
joint tonnage amounting to seven hundred and t 
thousand, two hundred and fourteen tons. 
It is a common opinion among geologists, *n‘' Jjit ''■y 
of vegetable origin, and tliat it has been 
present state bv the means of some chemical 
at this lime understood. Howe 
may at first siglit appear, it is s 
supported by 
of vast depositions ot matter, half way, c* 
tween jicrlect wood ami perfect pit coal ; "’1’"' jj, ■‘’J|;i’ 
obviously betrays its vegetable nature, h‘’^ iiS' '‘’..■r'’ 
respects so near an approximation to pit ces'h 
been generally distingui.shcd by the name ol P' y 
the most remarkable of these depositions eX‘i’'' >* 
thira, about thirteen miles soutii- west of Exctfi*’ 
