Formerly, sheets of stamps to be gummed were fastened in a frame and the
gum applied by hand with a large brush. They were then sent to the
drying room and hung up to dry. Now the process is entirely mechanical.
The sheets are fed into a machine in which they first pass under a
gummed roller. Then they are carried on an endless chain through a long
box filled with steam pipes and emerge at the further end dry and ready
to be pressed and perforated.

The subject of perforations is also worthy of some brief attention. The
first stamps were imperforate, necessitating the use of scissors or
other instrument in separating them. This was a manifest inconvenience.
In 1847, Henry Archer, an Irishman, began experimenting with machines
for perforating stamps. After a number of attempts he succeeded in
making a machine which was accepted by the English government and for
which, in 1852, he was allowed a compensation of £4,000. James M. Napier
greatly improved on this machine and adapted it for steam power.

The general principle of all perforating machines is a series of hollow
needles, which remove rows of small disks of the paper from between the
stamps, and thus fit them to be readily torn apart. For convenience of
reference and description philatelists have adopted, as a standard of
measurement, the space of two centimetres. The gauge of a perforation is
determined by the number of holes in this distance. Scales have been
prepared for measuring perforations but it would be superfluous to
attempt to describe them here. One of the largest perforations that has
been used for stamps has seven holes in two centimetres. This was used
on the stamps of France by Susse Freres, a firm of stationers. It was
done for the convenience of themselves and their customers. Some of the
stamps of Mexico have a still larger perforation gauging 5½. The