Improvements in Electric Signalling Apparatus.
Year: 1898

page_text: Date of Application, 21st Jan., 1898
Complete Specification Left, 20th Oct., 1898-Accepted, 26th Nov., 1898
Improvements in Electric Signalling Apparatus.
SILVANUS PHILLIPS THOMPSON, Morland, Chislett Road, West Hampstead,
Doctor of Science, do hereby declare the nature of this invention to be as
follows:-
:-
My improvements relate to the apparatus known as coherers used for receiving
electric waves in space-telegraphy. Instead of using a solitary point-contact, or
an incoherent mass of filings or metal particles as heretofore, I employ a number
of discrete conducting wires arranged in series, or in parallel, or in series and
parallel, in light contact, with means for regulating the contact pressures. I
have found clean wires of nickel. brass, or tinned copper, so arranged, to work
excellently. Or the contacts may be between different metals, or between metal
and carbon. In some cases I mount the coherer upon a vibrating sound board,
or upon a mechanical or electric tapper, such as a clock, or an electric trembler.
In some cases I cause the contacts to be made between stationary and revolving
surfaces.
Dated this 20th
1000
Improvements in Electric Signalling Apparatus.
I, SILVANUS PHILLIPS THOMPSON, F.R.S., of "Morland," Chislett Road, West
Hampstead, in the County of Middlesex, Doctor of Science, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:―
My improvements relate to apparatus of the kind known as coherers used for
receiving electric waves in telegraphy across space, and for the translation of
signals conveyed by such waves into ordinary electric current signals.
The first part of my invention relates to the grouping of contacts in coherers.
Instead of using a solitary point-contact, or the miscellaneous contacts produced
with a loose mass of metal filings or particles as heretofore in use as coherers,
I employ a number of discrete contacts arranged between conducting wires
which are grouped or arranged in series or in parallel or in some combination of
series and parallel grouping, forming thus groups of light or delicate contacts.
The second part of my invention relates to means for regulating the contact
pressures at the said points of contact. The third part of my invention relates
D
07

page_text: to means for renewal or changing of the actual contact surfaces in coherers by
mechanical motion, so as to bring about decoherence, after a signal, in a manner
more effectual than has hitherto been usual.
An example of the first part of my said invention is given in the apparatus
now to be described and which is illustrated in Figures 1 and 2 of the accompany-
ing drawings.
Figure 1 represents a simple combination of wires or metal hooks V1, V2 etc.,
hanging in light contact with fixed wires H¹ H2 etc., so that there may be more
than one such contact in series in the electric circuit of the receiving apparatus ;
and the group which is represented has two such sets of contacts in parallel with
one another. In this way the coherence or decoherence of the apparatus is no
longer dependent upon the coherence or decoherence of a single contact, thereby
rendering the action of the apparatus less conspicuous than a single contact would
be. The wires V1 V2 etc. hang nearly vertically and press lightly against the
fixed wires H¹ H² etc. The adjusting screw S and the tension spring T serve to
regulate the degree of pressure at the contacts by varying the inclination of the
system. The horizontal wires are held in an insulating support J. which may be
made of wood or ebonite. pivoted suitably or otherwise adjustably held upon a
frame or holder. Arrangements are made for the leading in and leading out
wires W of the circuit to be joined to the extremities of the group.
Figure 3 shews another grouping of vertical and horizontal wires. Figure 4
shews another grouping having three contacts in parallel with one another in
series with a second set of three contacts in parallel. Many varieties of such
grouping are obviously possible, and the contacts may be procured in many ways
that are obviously mechanically equivalent to the hanging wires here described.
I have found clean wires of such metals as nickel, brass, and tinned copper to
answer for this purpose. Or the contacts may be made between different metals
or between metal and carbon surfaces.
The second part of my invention is sufficiently described and illustrated by
reference to the adjusting screw of Figures 1 & 2, though I do not confine myself
to this particular form of adjustment.
The third part of my invention is illustrated in Figures 5 and 6. In Figure 5
is shewn a method of procuring a continual renewal of the contact surface by
causing one of the horizontal wires H to revolve slowly, as, for example, by
attaching it to a clock movement, or other convenient revolving mechanism, or
by means of a pulley P. In Figure 6 is shewn an ordinary coherer C of the
well-known Lodge kind hitherto in use, consisting of a small tube containing a
quantity of loose metallic filings or particles, to which in like manner a slow
movement of rotation is given either by means of a pulley P, by a clock, or
otherwise.
In conclusion I would say that I am aware of the prior use of the ticking
of a clock, and of other means to procure the mechanical vibration of a sounding
board or support on which a coherer is placed. I am also aware of arrangements
of a number of spiral springs lying in miscellaneous contact one upon another.
with a degree of pressure regulated by a screw and I do not consider either of
these arrangements to be within the scope of my invention.
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. As a coherer for the reception of electric waves apparatus such as is herein-
before described, and consisting of groups of discrete contacts arranged so as to
have at least two such contacts in series with one another, and at least two such
contacts in parallel with one another.
2. In apparatus for the reception of electric waves the combination of discrete
groups of contacts substantially as hereinabove described, with means for adjust-
ing the degree of pressure at the contacts of the same.

page_text: 3. In apparatus for the reception of electric waves, the combination of coherers
with a means of renewing or changing their contact surfaces, so as to produce
decoherence after a signal by means of a mechanically revolving mechanism,
substantially as described.
Dated this onth
Antah- 1000
W. P. THOMPSON & Co..
322, High Holborn London, W.C., Patent Agents for the Applicant.