bvious, then, that when a hole is
bored down through the upper impermeable layer to the surface of the
lake, the water will be forced up by the natural law of water seeking
its level to a height above the surface of the valley, greater or
less, according to the elevation of the level in the feeding column,
thus forming a natural mountain on precisely the same principle as
that of most artificial fountains, where the water supply comes from a
considerable height above the jet.

HOW MANY CUBIC FEET THERE ARE IN A TON OF COAL.--There is a difference
between a ton of hard coal and one of soft coal. For that matter, coal
from different mines, whether hard or soft, differs in weight, and
consequently in cubic measure, according to quality. Then there is a
difference according to size. To illustrate, careful measurements have
been made of Wilkes-barre anthracite, a fine quality of hard coal,
with the following results:

Cubic-feet Cubic feet
in ton of in ton of
Size of coal. 2,240 lbs. 2,000 lbs.

Lump 33.2 28.8
Broken 33.9 30.3
Egg 34.5 30.8
Stone 34.8 31.1
Chestnut 35.7 31.9
Pea 36.7 32.8

For soft coal the following measures may be taken as nearly correct;
it is simply impossible to determine any exact rule, even for
bituminous coal of the same district: Briar Hill coal, 44.8 cubic
feet per ton of 2,240 pounds; Pittsburgh, 47.8; Wilmington, Ill., 47;
Indiana block coal, 42 to 43 cubic feet.

The dimensions of the great wall of China and of what it is built.--It
runs from a point on the Gulf of Liantung, an arm of the Gulf of
Pechili in Northeastern China, westerly to the Yellow River; thence
makes a great bend to the south for nearly 100 miles, and then runs
to the northwest for several hundred miles to the Desert of Gobi. Its
length is variously estimated to be from 1,250 to 1,500 miles. For the
most of this distance it runs through a mountainous country, keeping
on the ridges, and winding over many of the highest peaks. In some
places it is only a formidable rampart, but most of the way it is
composed of lofty walls of masonry and concrete, or impacted lime and
clay, from 12 to 16 feet in thickness, and from 15 to 30 or 35 feet
in height. The top of this wall is paved for hundreds of mil