matical and scientific works,
are made by what is known as the "wax process."

This process was invented and patented by an Englishman named Palmer
about 1840, shortly after the discovery of the method of making
electrotype plates for printing purposes. He announced that he would
furnish artists with copper plates covered with a waxlike composition
on which they could make their own drawings, in a manner similar to
but much simpler than the method followed by the etcher on copper.
After receiving the artist's work, the plates were to be returned to
Palmer, who then made an ordinary electrotype of the engraving. A
circular, issued about 1841, gives the necessary instructions for
engraving, and the prices for the wax-coated plates and the subsequent
electrotypes, and shows many beautiful illustrations made by artists
of that time. It was then called the "glyphographic process."

The process was first introduced into this country by a firm of
printers in Buffalo, New York, and was used by them for several years
for illustrating the United States patent office reports until it was
superseded upon the introduction of photo-lithography and the
subsequent adoption by the government of a uniform standard for patent
drawings.

This process may be described in a general way as follows: A copper
plate having a highly polished surface is first blackened by the
application of a weak solution of sulphuret of potassium, or other
chemical which will oxidize the copper. Then a composition, made by
melting together in proper proportions, beeswax, zinc-white, and
paraffin, is "flowed" over the blackened surface, producing an opaque
whitish engraving ground. The thickness of the wax is varied according
to the subject to be engraved, but in general should not exceed that
of heavy writing paper. After it has been allowed to cool with the
plate lying perfectly horizontal, the wax is smoothed down to an even
thickness by a steel scraper, and the plate is then ready to receive
the engraving.

Taking for an example the engraving of a map, the original copy is
either photographed on the wax surface, or is transferred to it by
covering the back of the copy with red chalk and tracing over every
line with a steel point. The photograph, or the tracing, on the wax
must not be a reversed one, as might be supposed, but should "read
right." The outlines of the map are then gone over, with an engraving
tool which cuts out a small channel in the wax,