the other, as the paper at back retains sufficient glue to cause them to stick together if laid across one another; the whole must then be left to dry. When dry the groove should be knocked down on a flat surface, and for this the knocking-down iron screwed up in the lying press is perhaps the best thing to use. The groove is the projecting part of the
Martini's Folding Machine.
book close to the back, caused by the backing, and is the groove for the back edge of the mill-board to work in by a hinge; this hinge is technically called the "joint."
Machines.—There are many folding machines made by the various machinists; the working of them, however, is in nearly all cases identical. The machine is generally