nning up and down them. There
are shouts of the men, clanking of chains, and puffing of locomotives.

Marble is cut out in somewhat the same way as granite, but a valuable
machine called a "channeler" is much used. This machine runs back and
forth, cutting a channel two inches wide along the ends and back and
sometimes the bottom of the block to be taken out.

Marble is so much softer than granite that it is far more easy to
work. Cutting it is a simple matter. The saw, which is a smooth flat
blade of iron, swings back and forth, while between it and the marble
sand and water are fed. It does not exactly _cut_, but rubs, its way
through. The round holes in the tops of washstands are cut by saws
like this, only bent in the form of a cylinder and turned round and
round, going in a little deeper at each revolution. A queer sort of
saw is coming into use. It is a cord made of three steel wires twisted
loosely together. This cord is stretched tightly over pulleys and
moves very rapidly. Every little ridge of the cord strikes the stone
and cuts a little of it away.

There are varieties of marble without end. The purest and daintiest is
the white of which statues are carved; but there are black, red,
yellow, gray, blue, green, pink, and orange in all shades. Many are
beautifully marked. The inner walls of buildings are sometimes covered
with thin slabs of marble. These are often carefully split, and the
two pieces put up side by side, so that the pattern on one is reversed
on the other. Certain kinds of marble contain fossils or remains of
coral and other animals that lived hundreds of thousands of years ago.
In some marbles there are so many that the stone seems to be almost
made of them. When a slab is cut and polished, the fossils are of
course cut into; but even then we can sometimes see their shape. One
of the most common is the crinoid. This was really an animal, but it
looked somewhat like a closed pond lily with a long stem, and people
used to call it the stone lily. This stem is made up of little flat
rings looking like bits of a pipestem. The stems are often broken up
and these bits are scattered through the marble. The animals whose
shells help to make marble lived in the ocean, and when they died sank
to the bottom. Many of the shells were broken by the beating of the
waves, but both broken shells and whole ones became united and
hardened into limestone, one kind of which we call marble. Common
chalk is another