ratively little on the knife.

[Illustration: FIG. 10.--Mount Cutter's Knife]

To mend the torn back of a pair of leaves, a guard should be selected
a little longer than the height of the pages and well pasted with
white paste (see page 288). If the pair of leaves are not quite
separated, the pasted guard held by its extremities may be simply laid
along the weak place and rubbed down through blotting-paper. If the
leaves are quite apart, it is better to lay the pasted guard on a
piece of glass and put the edges of first one and then the other leaf
on to it and rub down.

On an outside pair of leaves the guard should be inside, so that the
glue may catch any ragged edges; while on the inside pair the guard
should be outside, or it will be found to be troublesome in sewing. In
handling the pasted guards care is needed not to stretch them, or they
may cause the sheet to crinkle as they dry.

[Illustration: FIG. 11.]

Plates must be guarded round the sections next them. When there are a
great many plates the back margin of each, to which a guard will be
attached, must be pared (see fig. 11, A), or the additional thickness
caused by the guards will make the back swell unduly. In guarding
plates a number can be pasted at once if they are laid one on another,
with about an eighth of an inch of the back of each exposed, the top
of the pile being protected by a folded piece of waste paper (see fig.
12). To paste, the brush is brought from the top to the bottom of the
pile only, and not the other way, or paste will get between the plates
and soil them. Guards should usually be attached to the backs of
plates, and should be wide enough to turn up round the adjoining
section, so that they may be sewn through. Should a plate come in the
middle of a section, the guard is best turned back and slightly pasted
to the inside of the sheet and then sewn through in the ordinary way.

[Illustration: FIG. 12.]

If plates are very thick, they must be hinged, as shown at fig. 11, B.
This is done by cutting a strip of about a quarter of an inch off the
back of the plate, and guarding with a wide guard of linen, leaving a
small space between the plate and the piece cut off to form a hinge.
It will save some swelling if the plate is pared and a piece of
thinner paper substituted for the piece cut off (see fig. 11, C). If
the plates are of cardboard, they should be guarded on both sides with
linen, and may even need a second joi