s because of its toughness and flexibility; because,
while protecting the back, it would bend when the book was opened and
allow the back to "throw up" (see fig. 1, A). When gold tooling became
common, and the backs of books were elaborately decorated, it was
found that the creasing of the leather injured the brightness or the
gold and caused it to crack. To avoid this the binders lined up the
back until it was as stiff as a block of wood. The back would then not
"throw up" as the book was opened, the leather would not be creased,
and the gold would remain uninjured (see fig. 1, B). This was all very
well for the gold, but a book so treated does not open fully, and
indeed, if the paper is stiff, can hardly be got to open at all. To
overcome both difficulties the hollow back was introduced, and as
projecting bands would have been in the way, the sewing cord was sunk
in saw cuts made across the back of the book.

[Illustration: FIG. 1.]

The use of hollow backs was a very ingenious way out of the
difficulty, as with them the backs could be made to "throw up," and at
the same time the leather was not disturbed (see fig. 1, C). The
method of "sawing in" bands was known for a long time before the
general use of hollow backs. It has been used to avoid the raised
bands on books covered with embroidered material.

If a book is sewn on tapes, and the back lined with leather, there is
no serious objection to a carefully-made hollow back without bands.
The vellum binders use hollow backs made in this way for great account
books that stand an immense amount of wear. They make the "hollow"
very stiff, so that it acts as a spring to throw the back up.

But although, if carefully done, satisfactory bindings may be made
with hollow backs, their use has resulted in the production of
worthless bindings with little strength, and yet with the appearance
of better work.

The public having been accustomed to raised bands on the backs of
books, and the real bands being sunk in the back, the binders put
false ones over the "hollow." To save money or trouble, the bands
being out of sight, the book would be sewn on only three or sometimes
only two cords, the usual five false ones still showing at the back.
Often only two out of the three bands would be laced into the board,
and sometimes the slips would not be laced in at all. Again, false
headbands worked by the yard by machinery would be stuck on at the
head and tail, and a "hollow"