Year: 1888

page_text: 1, EMILE BERLINER of Columbia Road, Washington in the District of Columbia,
United States of America, Electrician, do hereby declare the nature of this invention
and in what manner the same is to be performned, to be particularly described and
ascertained in and by the following statement :-
In the Specification of previous Letters Patent granted to me dated the 8th November
1887, and numbered 15,232 I have described a method of and apparatus for recording
and reproducing spoken words and other sounds; and in connection therewith, and as
a part thereof, I have described a process of producing a record of sound waves in
solid resisting material by photo-engraving, the phonautographic record of such sound
waves having first been produced as an undulatory line of even depth in a travelling
layer of non-resisting material.
My present invention consists of an improvement on such method or process of
recording sounds, and it has for its object the production of a record of sound
waves in solid resisting material, principally metal, by the process of direct etching;
whereby a solid unchangeable sound record is obtained more cheaply and more rapidly,
either upon a flat or upon a curved surface, without the delicate and intricate
manipulations incidental to the process of photo-engraving. All this will more fully
appear from the following detailed description, in which I shall freely refer to what
is shown and described in my aforesaid specification as a part of the now common or
public knowledge.
In accordance with the rules laid down in said Specification, I produced a phonauto-
graphic record upon a travelling layer of lamp-black, or other nou-resisting material;
then this phonautographic record was transferred by photo-engraving upon metal,
and the metallic record thus obtained was used for reproducing the recorded sounds.
In the course of my experiments I have found that in place of lamp-black, other
substances may be used as the non-resisting medium for receiving the original
phonautographic record, and I have also found that among the substances are such
as will resist the chemical action of acids, but which offer no perceptible mechanical
resistance to the movement of the recording stylus.
Upon this discovery, my present invention is based, and it consists, broadly
speaking, in producing a phonautographic record through a film of a suitable etching
ground deposited upon a travelling surface of resisting material, such as metal or

page_text: glass; and then subjecting said surface to the action of a suitable etching agent
which attacks said surface at the places only where the etching ground has been
removed by the recording stylus.
The etching ground, which is to serve as the non-resisting medium for the
phonautographic record, I prepare by dissolving beeswax, parafine, or other like
substance, in a suitable solvent. By preference, I use beeswax, and dissolve the
same in benzine so as to obtain a saturated solution. This solution is filtered, and
care is taken to exclude, as much as possible, all dust which is always present in the
ambient air.
In making the solution of beeswax, I preferably use a much greater quantity of
the latter than can be dissolved in benzine at the ordinary temperature, since
experience has shown that the ground thus obtained is more delicate and at the same
time resists the action of the etching-agent better than when the whole of the
is dissolved..
•
The surface which is intended to receive this ground, which may be a flat dise, or a
"cylinder of metal or glass, it should be smoothly polished, and must be cleansed and
dried. The wax solution is then poured over this surface so as to cover the same at
all points, and the solvent is then allowed to evaporate, which it does in one or two
minutes. An exceedingly fine film of wax then remains adhering to the surface of
the metal or glass, and the consistency of this wax is such that it offers no perceptible
mechanical resistance to the action of the recording stylus, while at the same time, it
resists the chemical action of ordinary etching agents.
In this respect, the film of wax deposited from the solution is quite different-from a
layer of wax produced by melting; the latter has such consistency, and adheres to the
supporting surface with such tenacity, that considerable force must be used to
penetrate the same and remove it from its support, while the wax film deposited in
the manner described is so delicate, that a camels hair brush will disturb it perceptibly.
Partly on account of the too great. sensitiveness of a single film, and also as an
additional protection against the action of the acids employed in the subsequent
etching, I ordinarily, but not recessarily, apply a second coating of the solution,
which when dry, leaves a filmn of wax of such thickness, as I have found to answer
all requirements.
plate or cylinder thus prepared, may be preserved indefinitely, and is at all times
in good condition to receive the phonautographic record. Such record is produced
by moving the prepared surface under a stylus actuated by sound waves to remove an
undulatory line of the non-resisting film from its support, whereby the latter is laid
bare along the said line; as is fully described in my specification above referred to;
and as is now well understood by those skilled in the art.
The plate or cylinder is 'then subjected to the action of a suitable etching agent,
the nature of which varies according to the material of the support. For metals,
such as zinc, copper or brass, diluted nitric, hydrochloric or other acid is used; while
for glass or other like materials fluoric acid or the fumes of the same must be used.
In either case I obtain upon the support, within a few minutes, an undulatory groove
of even depth representing the sound waves which acted upon the recording, stylus ;
and this groove.is of sufficient depth to guide and control a reproducing stylus, in
the manner set forth in my former patent specification.
By the use of the ordinary etching agents, the difficulty arises, that soon after the
action upon the metal base has commenced, the hydrogen, which is thereby set free,
accumulates in small bubbles along the traced lines and to both sides of the same,
forming a bar against the further action of the acid. In the ordinary process of
etching, this difficulty is overcome by brushing the surface of the plate from time to
time, whereby the gas bubbles are removed. This would be quite impracticable with
the delicate etching ground which I employ, since no brush could be found that would
be delicate enough to prevent the partial removal of the etching ground, and thereby
the accession of the acid to portions of the plate which must remain unaffected. I,
therefore, make use of an etching agent which consumes the hydrogen as soon as
the same is set free; and I have found that when the plate is of zinc, chromic acid,

page_text: or its substantial equivalents when used as the etching agent, will effectively prevent
the formation and accumulation of gas bubbles.
I do not, however, confine myself to any particular mode of etching, the ordinary
process being followed in this respect; the same is true of the practice. of re-biting,.
if a single exposure to the etching agent should prove to be insufficient to produce
a groove of sufficient depth. From a record produced in the manner described any
number of copies may be obtained by electro deposition, especially if the original.
record is etched in metal. In that case, however; I have found it advisable to
burnish the original record groove before the plate or cylinder is placed into the
depositing bath.
This is a very simple process, and consists in holding and gently pressing a pointed
burnishing tool in the record groove, while the plate or cylinder is rotated; the tool
is held in one hand, while the plate or cylinder is rotated by the other. In this
imanner the burnishing tool is guided through the record groove from one end to the
other, and the slightly granular structure of the etched groove is thus polished
without losing any of its essential characteristics. This process occupies only a very
few minutes, but though it improves, the galvano-plastic copy obtained from the
original record, it is not absolutely essential. In place of a special burnishing tool,
the reproducing stylus may be used, the point of which is ordinarily of hard metal,
such as iridium; so that the burnishing is effected by simply using the record once or
twice for reproducing the recorded sounds, in the ordinary manner.
It has been stated above, that the dissolved and filtered wax or other ground, should
be carefully protected against dust, which is always present in the surrounding air,
and it is obvious that the same précaution should also be taken with respect to the
plate or cylinder upon which the record is made. But experience has shown that it is
almost impossible to guard effectually against the accession of fine filamentary
particles of dust to and into the body of the tracing or etching ground. These dust.
particles are so fine that they cannot, as a rule, be detected by the most searching"
inspection of the prepared plate; but they become very conspicuous and a very
serious source of annoyance when the record is made. As the recording stylus passes.
through the wax or other ground, a fine undulatory line of the latter is removed, and
the removed material drops away from the stylus as soon as removed, so that the
point of the stylus always remains clean. This, however, is only the case
when the ground is free of filamentary impurities; but if filaments of dust are
imbedded in the ground, they adhere to the stylus and together with a coating. of
the ground are dragged through newly formed grooves, whereby the latter becoine.
uneven and receive ragged edges which seriously impair the accuracy of the record.
I have discovered an effective means for overcoming this difficulty, and it consists
in simply, moistening the record surface with a fluid that slightly adheres to the
ground, and keeping it moist while the record is being made.
I have found strong
alcohol to be very effective for this purpose, when wax is used as the tracing ground,
and it is used by pouring, it over the ground just before the plate or cylinder is started.
to move under the recording stylus. The alcohol evaporates rapidly, but not so
rapidly as to disappear entirely before the record is finished; and this record now
shows no trace of inequality; the lines being as sharp and well defined as if cut by a
graver. The point of the stylus remains quite clean, and it seems as if the filamentary,
particles had disappeared.
I have no definite theory by which to explain this surprising result. It is possible
that the exceedingly fine dust particles are forced against the walls of the grooves and
are there held, when the ground is in the peculiar state of dampness which it receives
when alcohol is poured over the same; it is also possible that these particles of dust,
being probably of organic matter; are dissolved by the alcohol; and it is also possible
that both causes operate to keep the point of the stylus clean so as to make a sharp
and well defined record. But whatever be the mode of action of the alcohol poured
over the ground, its effect is highly beneficial,.and 'its 'use.constitutes one.of.iny
improvements.
The film of ground which I employ is so exceedingly thiu, that it is practically

page_text: colorless and transparent; the record is for this reason almost invisible to the naked
eye. In some cases, however, it is desirable to be able to inspect and scrutinize the
record before it is exposed to the action of the etching agent, or to watch the progress
of the record; and for this reason it is advisable to slightly color the ground before
the record is made.
I accomplish this by exposing the record surface, after the etching ground has been
applied, to the cold smoke of a flame, preferably to the smoke of the flame of burning
camphor, whereby a very light deposit of lamp-black is made upon the ground, and
whereby the tracings which are afterwards made by the stylus become visible as pale
lines upon a grey ground,
Care must be taken in this process to hold the plate or cylinder at such distance
from the flame, that the heat of the latter does not perceptibly affect the wax ground,
so that the latter does not melt, whereby its peculiar consistency that adapts it to be
impressed by a minimum tracing force, would be changed.
The application of alcohol or other dampening fluid, as above described, does not
disturb the fine layer of lampblack and acts, in addition to its principal function of
keeping the point of the stylus clean, and the tracings sharpe and well defined, also as
a lubricator, that diminishes the friction of the stylus.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. The method or process of producing a record of sound waves in solid, resisting
material for reproduction of the recorded sounds, which consists in covering the
surface of such material with a film of etching ground that offers no perceptible
mechanical resistance; then making a phonautographic record upon and through the
etching ground, and then exposing the record to the action of a suitable etching agent
substantially as described.
2. The method or process of producing a record of sound waves in solid, resisting
material for reproduction of the recorded sounds, which consists in depositing upon
the surface of such material a film of wax from a solution of the same in a suitable
menstruin; then making a phonautographic record upon and through the wax film,
and then exposing the record to the action of a suitable etching agent; substantially
as described.
3. The method or process of producing a record of sound waves in solid, resisting
material for reproduction of the recorded sounds, which consists in depositing upon
the surface of such material a film of wax from a solution of the same in benzine,
then making a phonautographic record upon and through the wax film, and then
exposing the record to the action of a suitable etching agent; substantially as
described.
4. The method or process of preparing solid surfaces for the reception of n
phonautographic record, which consists in depositing upon said surfaces a film of
tracing or etching ground, and then moistening such film with an adhering film;
substantially as described.
5. The method or process of preparing solid surfaces for the reception of a
phonautographic record, which consists in depositing upon said surfaces a film of wax,
and then moistening the wax film with alcohol; substantially as described.
Thated thi 14th M... 1000
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London,
Agent for the Applicant.