An engraver is seldom expert in more than one style of work. Each makes
a specialty of some branch, portraiture, lettering, scroll-work, etc.
For this reason several engravers are usually employed on each die for a
postage stamp. And in this inability of one individual to do all styles
of work equally well lies one of the great securities against
counterfeiting.

In the course of making a die, proofs are usually taken and these are
much prized by collectors.

The die being finished, it is placed in a bath of cyanide of potassium
and heated until the vessel containing it is red hot. This process
occupies from fifteen minutes to half an hour for dies but may take as
much as an hour for a large plate. The die is then transferred to a bath
of oil, to cool and temper it. By this process it is thoroughly
hardened.

[Illustration: From "The Popular Science Monthly," Vol. XLVI, No. 5.
Copyright, 1895, by D. Appleton & Co.]

In the case of postage stamps, where it is desired to exactly duplicate
the design many times on a plate, recourse is had to transfer rolls. A
transfer roll is a piece of soft steel, in shape a cross section of a
cylinder. The edge is sufficiently wide to receive an impression from
the die. We show you here a picture of a transfer press. From each side
of the roll projects a small pin or trunion. These pins form an axle
for the roll and by them it is held in the carrier of the press. A is
the roll in the carrier. The die is placed on the table or bed B. The
roll is held against the die with a pressure of many tons, obtained by
compound leverage. By means of the wheel, E, and the connecting pinion