e copper plate with a tool resembling a
cabinet maker's toothed plane iron, except it is rounded at the end.
The teeth are very fine, ranging from forty to one hundred and twenty
to the inch in different tools. This tool is called a "Bercier," or
"rocker." The rounded edge allows the tool to be rocked across the
plate, the rocking motion causing the teeth to form indentations in
the copper. The rocking has to be continued until the surface of the
plate is completely covered, and it then presents an appearance like
velvet. Rocking in from forty to sixty directions is necessary to
cover the plate properly. The durability of a mezzotint plate depends
entirely upon the pressure put upon the rocker, and the depth to which
it penetrates the copper. After the ground is thus laid, the outline
is sketched in on the rocked surface, which takes the pencil easily,
and then with steel scrapers and burnishers the light and middle tints
are worked down, leaving undisturbed the portions of the surface where
the strongest blacks are to be. From time to time, a print is taken
from the plate, to note the progress of the work, which advances
slowly to the finish. On account of the length of time necessary for
the laying of the ground and the scraping of the plate, many artists
hesitate to attempt mezzotint plates. There are very few men in this
country to-day who do mezzotint engraving, which, considering the
results to be obtained, seems somewhat surprising.

For flesh tones, drapery, and landscapes it has no equal. The velvety
richness of the blacks, the beautiful gradations of the middle tones,
and the extreme delicacy of the light tints give the artist a power of
expression not obtainable by any other method of engraving. Besides
this, as the engraving is done on the bare copper, the artist can see
at all times the progress of his work without having to take off the
wax ground as he must in making an etching. This is a great advantage,
for as the effect of each stroke can be plainly seen on the plate, the
element of uncertainty which always attends the production of an
etching is entirely eliminated, and it is then simply a question of
skill with the scraper. The difficulty of obtaining rockers is one
great drawback. I doubt if one could be obtained in New York to-day.
The teeth have to be very accurately cut, and a perfect tool has a
value to an engraver that cannot well be estimated. The lack of demand
has prevented their manufacture