nknote company and there are very few men who thoroughly
understand operating them. A turn of a screw or a variation of a single
cog will change the result entirely. Finally the work of the lathe is
often reversed, so that the line which is cut by the graver and should
print in color prints white, and vice versa. It would not be possible to
imitate this by hand engraving.

Printing from line-engraved plates is largely done by hand presses. The
ink used is very thick. When black it is made of finely pulverized
carbon, mixed with oil. Colored inks are composed of zinc white and dry
colors, ground in oil. The colors are animal, vegetable or mineral. The
latter cause the plates to wear out rapidly. Green is an especially
destructive color. In recent years aniline colors have been largely
employed. They afford an elaborate range of shades and color
combinations which are most puzzling to describe. Soluble inks are much
used by the leading English firm of stamp printers. They are very
sensitive to water and are regarded as one of the best preventatives of
the cleaning of used stamps. Beautiful results are obtained by printing
stamps in two colors. Of course, this necessitates the use of two plates
for each design. This also gives rise to some interesting varieties,
caused by one part of the design being printed upside down. Such
oddities are scarce and are highly valued by philatelists.

When a plate is to be printed from, it is first warmed, then the ink is
applied and rubbed into the lines with a pad. The surface of the plate
is wiped off with a cloth, then with the hand and lastly, polished with
whiting. A sheet of dampened paper is next laid on the plate and the
whole is passed under the roller of a press, which forces the paper into
the lines of the plate, where it takes up the ink. When the plate is
deeply engraved the ink seems to stand up from the surface of the paper
in ridges and some times we find corresponding depressions on the backs
of the stamps. The sheets are then dried, gummed and dried again. They
are now so much curled and wrinkled that they are placed between sheets
of bristol board and subjected to hydraulic pressure of several hundred
tons which effectively straightens them out.

The second process of printing from metallic plates is called
typography. The plates for this process are the exact reverse of those
engraved in _taille douce_. Instead of the design being cut into the
plate, it is on the sur