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erage thichness of workable mercantile coal is about eleven
feet. Neither the exact size of this coal field, nor the extent
of any of its seams can be determined unless by a trigono-
metrical survey. The estimates made here are only approxi-
tions derived from detached surveys of different tracts of dif-
ferent owners. The most reliable estimates agree in giving
the number of acres of the Big Vein at about 20,000.

The coal from this coal field alone is sufficient to supply the
whole Union for centuries, and practically may be said to be
inexhaustible.

Quality of the Goal.—For a long time the superior excel-
lence of this coal was questioned by rival interests, but pro-
longed experience with numerous scientific and practical
tests have established its character as superior to any other
accessible in this country for the generation of steam, either
for navigation or manufacturing purposes, for the reduction of
iron ores and for ordinary domestic uses. This has been so
thoroughly conceded that any proof to support it is unnecessa-
ry. It is the common judgment of the country, alike con-
firmed by laboratory tests and the practical trial of ocean
steamship lines traversing the great Atlantic.

MIDDLE COAL FIELD or ALLEGHANY.

Between Negro and Meadow Mountains there is the Mid-
dle coal field of Alleghany. This coal approaches nearest
in its composition to the Pittsburg coal. It has not yet been
used except for domestic purposes in the neighborhood. It
is a fine compact coal, and is only prevented from more gen-
eral use by want of means of transportation.

Western Coal Field of Allegliang County.—This lies in the
Valley of Youghiogheny river, and will become a matter of
great interest, not so much for supplying foreign demand, as
for the manufacture of the iron ores, which are associated
with it here in large quantities. This coal is much of the
same quality as the coal in the Middle field.

The coal veins in this region are :
A two foot vein.
A four foot vein.
A four foot vein.
A six foot vein, and
A five foot vein.

All these coal fields, from the peculiar formation of the
country being intersected by ravines, present great facilities
for being worked. Many of them drain themselves, and can
be ventilated at a trifling expense. In the value of coal lands