has been
erected.

Water in the form of vapour is a great enemy of books, the damp
attacking both outside and inside. Outside it fosters the growth of a
white mould or fungus which vegetates upon the edges of the leaves, upon
the sides and in the joints of the binding. It is easily wiped off, but
not without leaving a plain mark, where the mould-spots have been. Under
the microscope a mould-spot is seen to be a miniature forest of lovely
trees, covered with a beautiful white foliage, upas trees whose roots
are embedded in the leather and destroy its texture.

Inside the book, damp encourages the growth of those ugly brown spots
which so often disfigure prints and "livres de luxe." Especially
it attacks books printed in the early part of this century, when
paper-makers had just discovered that they could bleach their rags,
and perfectly white paper, well pressed after printing, had become the
fashion. This paper from the inefficient means used to neutralise the
bleach, carried the seeds of decay in itself, and when exposed to any
damp soon became discoloured with brown stains. Dr. Dibdin's extravagant
bibliographical works are mostly so injured; and although the Doctor's
bibliography is very incorrect, and his spun-out inanities and
wearisome affectations often annoy one, yet his books are so beautifully
illustrated, and he is so full of personal anecdote and chit chat, that
it grieves the heart to see "foxey" stains common in his most superb
works.

In a perfectly dry and warm library these spots would probably remain
undeveloped, but many endowed as well as private libraries are not in
daily use, and are often injured from a false idea that a hard frost and
prolonged cold do no injury to a library so long as the weather is dry.
The fact is that books should never be allowed to get really cold, for
when a thaw comes and the weather sets in warm, the air, laden with
damp, penetrates the inmost recesses, and working its way between the
volumes and even between the leaves, deposits upon their cold surface
its moisture. The best preventative of this is a warm atmosphere during
the frost, sudden heating when the frost has gone being useless.

Our worst enemies are sometimes our real friends, and perhaps the best
way of keeping libraries entirely free from damp is to circulate our
enemy in the shape of hot water through pipes laid under the floor. The
facilities now offered for heating such pipes from the outside are so