The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1853-08-04
THE UNITED STATES COAST SURVEY.


THE ELECTROTYPING PROCESS.
Among the most valuable contributions in scien.
t6c point of view, the instruments employed in
the United States Coast Survey. These occupy a
place to the right Of the Fortysecond street entrance
AS very few of the thousands of vsters to the Palace
understand their use, or are even acquainted with
their names, we intend giving description of each
from time to time. Meanwhile we present the follow
ing description of the process of eectrotyping to our
readers. 1t is very important art as will be seen
from this account =
The Coast Survey exhibits three sets Of eectrotype
platesIhe larger is 42x3s ncbes the ssx27 and
the smaller 22x1S; these the general sizes OF the
Coast Survey charts. Zach contains the original
plate that produced BY the engravers the ,roy
mould taken from the original and the eecrotyOe up.
Of the original taken from the mould This duplic .te
faithful fac siBiiie Of the original that the one
cannot be distinguished from the other the most aten
tive examination fails 10 detect difference This ey ct
Of copy obtains other art of cops ing forms;
even the common printing type, simple their forms
are differ somewhat from the steel punches used 10 make
the matrices but when we reflect what largo and
celicately wrought surfaces exactly duplicated
by the electrotyre, the beauty Of the art in com
psrhon With all other pasac Operations becomes
conspicuous. The largest plates of the Coast
Survey present surfacs Of over ten square
feet, eaboratey wrought that msgnifyinr glass l.
required for viewing the mnuti before The real extent
and difficulty of the work becomes apparent. Sucs a
plate requires set of sku engravers three to five
~
be Duplicated in the ab)ratory OF he survey three
short days perfectly that the artist who has abored
daily for years cannot dscover which Ia the plats
he produced.
The practical result of this exact multi aatou OF
forms is that the eDgrsyer having done his work.
nnity Of prints may be obtained and these all Of the
first clssa or new impressions, tho printers style
those taken before the plate begins 70 show the
printing The plate being gradualy worn out by the
printing the impressions decrease in vaue until they
longer represent the design OF the Hence large
engavnPs must be costly and the number limited unless
the expense OF engraving E Otter Incurred This crc1m
stance early occurred 10 Prof Bsche limiting the
fusion and pepetuaon OF the useful of the survey
and he accordingly caused experimental trials Of eec
tiotype TO be made. But the cat which
attended the new art, the repetition Of the best European
processes gave but unsatisfactory results IL was found
that the eectrotype plate deficient mechanical
virtues as to be Of but little use and very often would be
so frsge 10 whole or In parts. to break like cake Of
sandsone but worse than all these defects, deposited
copper was apt to adhere firmly the original plate
a. to wholly spoil It, converting monument Of pstieucs
perseverance, and artistic ski into sighte OF
copper; and the known recommended for pre-.
venting the adhesion. defective of they were obite
rate the finest parts of the engraving
NO cure Tor there casualties appeared in the Office OF
the Coast Survey except from radical examination OF
the principles OF the art and thorough application Of
the sciences involved 10 the principles This has Welded
even unhoIed for resuts Reforming oarge elecroypes
In the Coast Survey laboratory certain pro-
cese as the moulding of bricks
The first grand result obtained by the Coast Survey