arly date. It was introduced to Europe by the Arabs about the 10th
century A.D. It was made of linen or rags and did not vary greatly from
the rag paper of to-day. As the process of manufacture is fully
described in the book on paper (No. 13) of this series, description is
not necessary here. Paper was not much used in Europe until the
invention of printing. Being much less substantial than vellum it did
not commend itself for the making of manuscript books. Paper was,
however, immediately found to be much better suited to printing than any
other material, and with the advent of the printed book it very quickly
drove other writing materials out of common use. Owing to its having
some resemblance to papyrus it was given the old name, the word paper
being derived from papyrus.

Late in the 19th century a new writing material made of wood or other
flexible fibre treated with chemicals and loaded with clay was invented,
to which we also give the name paper. This new material has almost
entirely driven the old rag paper out of the field and is now the paper
of commerce. Much of this material is far inferior to rag paper. The
inferior qualities of it, at any rate, lack durability even when not
exposed to wear. It is good enough for the great number of uses where
permanence is not required. It should only be used for books of
permanent value, especially for records and historical material, when
there can be no doubt of the care used in the manufacture and the
quality of the fibre employed. A 15th-century book on rag paper is as
good to-day as the day it was printed. Most of the paper now in use
possesses no such lasting qualities.

In addition to these three leading materials, much use has been made of
tablets (Latin _tabella_). The commonest form of tablet was a thin board
with one or both sides slightly cut away in such a way as to leave a
narrow rim all around. The shallow depression inside this rim was then
filled with wax sufficiently stiff to hold its position in ordinary
temperatures but sufficiently soft to be easily marked with a sharp
instrument called a stylus. The writing could be easily erased by
rubbing with a hard smooth object, perhaps a ball at the reverse end of
the stylus, and the wax was then ready for another impression. Sometimes
these tablets were made of wood covered with paint or a composition from
which the writing could be easily washed off. This was the prototype of
the schoolboy's slate of to-day