ess of the
stone, and that the remaining part of the thickness is black. Stones are
often found with such a division of colors, not only white and black,
but of all other hues.

Now, the artist takes such a stone as this, and marks out some design
upon one side of it, say upon the white side. Perhaps the design may be
the figure of a man. Then he cuts away all the white of the stone except
the figure; and the result is, that he has the figure of the man, or
whatever else his design may be, in white, on a black ground, and the
whole in one piece of stone, all solid.

Besides stone, shell is often used for cameos; many shells being pink,
or of some other such color on the inside, and white towards the
outside. In such a case, the figures of the design would be pink, or
whatever else the color of the stone might be, on a white ground.

The artists of Rome are celebrated for making beautiful cameos, both in
shell and in stone. The figures are very nicely drawn, and are very
beautifully cut, and when finished are set as pins, bracelets, and other
ornaments.

The _mosaics_, on the other hand, are made in a very different way. In
these, the design is represented by different colored stones or bits of
glass worked in together, with great care, in an opening made in the
material serving for the groundwork. Rollo and Charlie went into one
of the shops, and saw a man making one of these mosaics. He was working
at a table. On one side was a small painting on a card, which was his
model. He was copying this painting in mosaic. The bits of glass that he
was working with were in the form of slender bars, not much larger than
a stiff bristle. They were of all imaginable colors--the several colors
being each kept by itself, in the divisions of a box on the table. The
man took up these bars, one by one, and broke off small pieces of them,
of the colors that he wanted, with a pair of pincers, and set them into
the work. He put them in perpendicularly, and the lower ends went into
some soft composition, placed there to receive and hold them. The upper
ends, of course, came together at the surface of the work.

The man who was making the mosaic told Rollo, that as soon as he had
finished placing the pieces for the whole design, he should grind off
the surface so as to make it smooth, and polish it. It would then have
the appearance of a painted picture.

You would think that as the colors of the design are thus represented by
separat