were thirty, of the
diameter of five inches. The mountain was moved by four windlasses, and
sometimes by two; each required thirty-two men: it was raised and
lowered by screws, to remove the balls and put them on the other side.
When the road was even, the machine moved 60 feet in the hour. The
mechanic, although continually ill from the dampness of the air, was
still indefatigable in regulating the arrangements; and in six weeks the
whole arrived at the river. It was embarked, and safely landed. Carburi
then placed the mass in the square of St. Peter's, to the honor of
Peter, Falconet, Carburi, and of Catherine, who may always, from her
actions, be classed among illustrious men. It is to be observed, that in
this operation the moss and straw that was placed underneath the rock,
became by compression so compact, that it almost equalled in hardness
the ball of a musket. Similar mechanical operations of the ancients have
been wonderfully exaggerated by their poets."

COMPARATIVE SKILL OF THE ANCIENTS AND MODERNS IN MECHANICS.

Many persons suppose, and maintain, that the grandeur of the monuments
of the ancients, and the great size of the stones they employed for
building purposes, prove that they understood mechanics better than the
moderns. The least knowledge in mechanics, however, will show this
opinion to be erroneous. The moderns possess powers which were unknown
to the ancients, as the screw, and the hydraulic press, the power of
which last is only limited by the strength of the machinery. The works
of the ancients show that they expended a vast deal of power and labor
to gratify the pride and ambition of kings; but the moderns can do all
these things much easier, and in far less time, whenever they deem it
proper. There was nothing in ancient times to be compared with that
daring, ingenious, and stupendous monument of engineering skill--the
Britannia Tubular Bridge, across the Menai straits--projected, designed,
and built by Robert Stephenson, the famous English engineer. He had
previously built a similar but smaller structure--the Conway Tubular
Bridge.

THE BRITANNIA TUBULAR RAILWAY BRIDGE.

Had this stupendous fabric existed in ancient times, it would have been
regarded as the _first_ of the seven wonders of the world. Greater and
more expensive structures have been raised, but none displaying more
science, skill, and ingenuity, and none requiring such tremendous
mechanical power to execute