0
miles long by 20 miles wide, and covering about 175 square miles. Much of
the coal which lies deep in these coal-measures will always remain
unattainable, owing to the enormous thickness of the strata, but a
careful computation made of the coal which can be worked, gives an
estimate of no less than 2750 millions of tons. There is a grand total of
two hundred and forty-four seams, although about half of them are
unworkable.

Beside other smaller coal-producing areas in Germany, the coal-fields of
Silesia in the southeastern corner of Prussia are a possession unrivalled
both on account of their extent and thickness. It is stated that there
exist 333 feet of coal, all the seams of which exceed 2-1/2 feet, and
that in the aggregate there is here, within a workable depth, the
scarcely conceivable quantity of 50,000 million tons of coal.

The coal-field of Upper Silesia, occupying an area about 20 miles long by
15 miles broad, is estimated to contain some 10,000 feet of strata, with
333 feet of good coal. This is about three times the thickness contained
in the South Wales coal-field, in a similar thickness of coal-measures.
There are single seams up to 60 feet thick, but much of the coal is
covered by more recent rocks of New Red and Cretaceous age. In Lower
Silesia there are numerous seams 3-1/2 feet to 5 feet thick, but owing to
their liability to change in character even in the same seam, their value
is inferior to the coals of Upper Silesia.

When British supplies are at length exhausted, we may anticipate that
some of the earliest coals to be imported, should coal then be needed,
will reach Britain from the upper waters of the Oder.

The coal-field of Westphalia has lately come into prominence in
connection with the search which has been made for coal in Kent and
Surrey, the strata which are mined at Dortmund being thought to be
continuous from the Bristol coal-field. Borings have been made through
the chalk of the district north of the Westphalian coal-field, and these
have shown the existence of further coal-measures. The coal-field extends
between Essen and Dortmund a distance of 30 miles east and west, and
exhibits a series of about one hundred and thirty seams, with an
aggregate of 300 feet of coal.

It is estimated that this coal-field alone contains no less than 39,200
millions of tons of coal.

Russia possesses supplies of coal whose influence has scarcely yet been
felt, owing to the sparseness of the p