The Menai Bridge, one of the most stupendous works of art that has been
raised by man in modern ages, consists of a mass of iron, not less than
four millions of pounds in weight, suspended at a medium height of about
120 feet above the sea. The consumption of seven hanhels of coal would
suffice to raise it to the place where it hangs.
The great pyramid of Egypt is composed of granite. It is 700 feet in the
side of its base, and 500 in perpendicular height, and stands on eleven
acres of ground. Its weight is, therefore, 12,760 millions of pounds, at a
medium height of 125 feet; consequently it would be raised by the effort
of about 630 chaldrons of coal, a quantity consumed in some founderies in
a week.
The annual consumption of coal in London is estimated at 1,500,000
chaldrons. The effort of this quantity would suffice to raise a cubical
block of marble, 2,200 feet in the side, through a space equal to its own
height, or to pile one such mountain upon another. The Monte Nuovo, near
Pozzuoli, (which was erupted in a single night by volcanic fire,) might
have been raised by such an effort from a depth of 40,000 feet, or about
eight miles.--_Cabinet Cyclopaedia_, vol. xiv.
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