That ton and a half of resistance of gas in front must be much more
than overcome by gas behind.

But the least use of explosives is in war; not over ten per cent is so
used. The Mont Cenis tunnel took enough for 200,000,000 musket
cartridges. As much as 2,000 kegs have been fired at once in
California to loosen up gravel for mining, and 23 tons were exploded at
once under Hell Gate, at New York.

How strong is this gas? As strong as you please. Steam is sometimes
worked at a pressure of 400 pounds to the inch, but not usually over
100 pounds. It would be no use to turn steam into a hole drilled in
rock. The ordinary pressure of exploded gas is 80,000 pounds to the
square inch. It can be made many times more forceful. It works as
well in water, under the sea, or makes earthquakes in oil wells 2,000
feet deep, as under mountains.

The wildest imagination of Scheherezade never dreamed in _Arabian
Nights_ of genii that had a tithe of the power of these real forces.
Her genii shut up in bottles had to wait centuries for some fisherman
to let them out.




NATURAL AFFECTION OF METALS

"Sacra fames auri." The hunger for gold, which in men is called
accursed, in metals is justly called sacred.