" IN TELEGRAPHIC INSTRUMENTS.
Year: 1876

page_text: LETTERS PATENT to Saint John Vincent Day, of Glasgow, in the County of
Lanark, North Britain, Civil Engineer, for the Invention of "IMPROVEMENTS
"
IN TELEGRAPHIC INSTRUMENTS.' A communication from Georges Dubern,
of Allipore, near Calcutta, in the Empire of British India.
PROVISIONAL SPECIFICATION left by the said Saint John Vincent Day at the
Office of the Commissioners of Patents on the 22nd September 1876.
SAINT JOHN VINCENT DAY, of Glasgow, in the County of Lanark, North Britain,
Civil Engineer. "IMPROVEMENTS IN TELEGRAPHIC INSTRUMENTS."
This Invention, which relates to improvements in telegraphic instruments, consists
of mechanical arrangements or constructions of apparatus applicable to instruments.
in which there is employed an electro-magnet attracting and repelling an armature
or coils acting directly on an armature, and also of means for increasing the sound
produced by the strokes of the armatures in such instruments as are called "sounders."
In accordance with this Invention the armatures of sounders or those of bells or
analogous apparatus or the tongues of "relays" or similar mechanism are pivoted
about the centre of gravity and placed crosswise between the magnets or electro-
magnetic poles or coil poles, so that the pivoting of the armatures or tongues is in a
straight line with the said electro-magnet or coil poles. By this arrangement the
armature when acted upon by the current is subjected to two equal forces acting
normally in opposite directions (one at each end of the armature) and thus tending
to make the armature simply revolve about its centre without any increase of
pressure being caused on the bearings through the exertion of those forces.
The electro-magnet poles employed under this Invention may be cylindrical with
a groove corresponding to the ends of the armature made in them, or they may be
constructed in the form of a horse-shoe, which latter form is more advantageous
when employed with direct working sounders.
The friction of the pivot of the armature herein-before referred to is almost
entirely avoided by either of the arrangements herein-after described.
Under one arrangement the apparatus employed for this purpose consists of two
springs fixed one at each end of the armature, their opposite extremities being
secured to a lever moveable about its centre, which is vertical. These springs by

page_text: their upward pull lift up the armature from its lower bearings and by their slant
(which is adjustable by any of the well known means) act as antagonistic springs.
Under another arrangement a spiral spring is placed concentrically with the
axle of the armature and connected at one end to a slide fixed to the axle by means
of a screw or analogous apparatus. The other end of the spring is fixed to a piece
of metal which may have a circular motion, a jamb nut or tangent screw being
employed to keep the said piece of metal in its proper position. By placing the
slide so as to stretch the spiral spring, the total weight of the armature is supported
by the spring, any circular motion of the piece of metal herein-before referred to
producing a twist of the spiral spring which causes it to act as an antagonistic spring.
Modifications of the herein-before described apparatus may also be used.
Under this Invention a metallic split sounding pipe is employed in conjunction
with the armature, an annular space being left between the said arinature and the pipe.
The pipe is fixed to the armature at one end, and its other end which is free strikes
against platinum points, which limit its motion. This end may be furnished with
platinum or translation springs.
The advantage of a pipe over a solid piece of metal is that it produces a much
higher and louder note for a given intensity of the impelling force of the electro-
magnet.
Where it is not objectionable on account of size, the split sounding pipe is
prolonged right and left on each side of the armature.
The only condition for success with regard to the sound produced is that where
the sounding pipe touches the armature the joint must be perfect, the slightest play
at that part reducing the intensity of the sound; soldering the pipe to the armature
answers well, and stout tin (not annealed) is a good material for making such a
pipe.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Saint John Vincent Day in the Great Seal Patent Office on the.
21st March 1877.
SAINT JOHN VINCENT DAY, of Glasgow, in the County of Lanark, North Britain,
Civil Engineer. "IMPROVEMENTS IN TELEGRAPHIC INSTRUMENTS." A communica-
tion from Georges Dubern, of Allipore, near Calcutta, in the Empire of British
India.
The said Invention, which relates to improvements in telegraphic instruments,
consists of mechanical arrangements or constructions of apparatus applicable to
instruments in which there is employed an electro-magnet attracting and repelling
an armature or coils acting directly on an armature, and also of means for increasing
the sound produced by the strokes of the armatures in such instruments as are
called "sounders."
In accordance with the said Invention the armatures of sounders or those of bells
or analogous apparatus or the tongues of "relays " or similar mechanism are pivoted
about the centre of gravity, and placed crosswise between the magnets or electro-
magnetic poles or coil poles, so that the pivoting of the armatures or tongues is in a
straight line with the said electro-magnet or coil poles. By this arrangement the
armature, when acted upon by the current is subjected to two equal forces acting
normally in opposite directions (one at each end of the armature) and thus tending
to make the armature simply revolve about its centre without any increase of
pressure being caused on the bearings through the exertion of those forces.
And in order that the said Invention may be properly understood, I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, reference being had to the
annexed Sheet of Drawings, and to the letters and figures marked thereon, that is
to say,
Figure 1 represents the typic disposition of electro-magnet and armature. A is

page_text: the armature; B, B¹, the electro-magnet poles (these may be cylindrical with a
groove corresponding to the ends of the armature, or in the form of shoes, as
represented by dotted lines, this last form being more advantageous to direct
working sounders); C, C, is the axle terminated by points.
The friction of the pivot of the above armature is almost totally avoided by
either of the following plans:-
First. Two springs A, A¹, (Figure II.) are fixed one at each end of the armature B,
each of their other extremities is also fixed to a lever C movable about its central
part, its centre being vertically above the centre of the armature, as represented.
These springs by their upward pull lift up partly or totally the armature from the
lower bearings, and by their slant adjustable by any of the many well known ways
act as antagonistic springs. Figure III. represents another such arrangement in
principle and way of action; it is applicable to more costly instruments, where
perfection of working is of greater importance than cost.
Second. In Figure IV., A is the armature; B, the axle; C, a spiral spring con-
centrical with the axle B; D is a small slide to which one end of the spring is
fixed; this slide may be fixed at any part of the axle B by means of the set
screw E. The other end of the spring is fixed to a piece F which may take a
circular motion on the central stem G, so constructed as to keep G in the same
plane. H is the core plate of the electro-magnet; I, a jamb to keep F in its proper
position. Instead of a jamb nut an ordinary tangent screw working in F
may be
employed when very fine adjustment is required. By placing the slide D so as to
stretch sufficiently the spring C, the total weight of the armature is supported by it,
any circular motion of the nut F about the central stem G producing a twist of the
spring C, causing it to act also as an antagonistic spring.
Figure V. represents a similar plan in principle and way of action, only with such
necessary modifications as to render it applicable to such instruments in which the
armature is to be as light as possible, namely to relays.
The above described armature might be called "frictionless armature." A is tho.
armature; B, the pivot; C, a small bracket for the top bearing of the armature; iu
polarised instruments this bracket is to be made of soft iron, having provided in it
a non-magnetic bearing for the end of the pivot B; magnets applied to this bracket
polarise the armature. D is a stirrup to which one end of the spring is fastened;
the other end of the spring is fixed to a small stem E able to turn with a moderate
friction through the picce F. F is a screw bored through and through and filed
flat on two or four of its sides; G is a guide supported by the electro-magnet
core plate, or where no soft iron cores are employed by an additional bracket, as
represented by H. The guide G has a square hole which allows the piece F to
work up and down without turning from side to side. I is a nut catching in the
tread of the slide rod F. By screwing or unscrewing the nut I the spring J is
stretched more or less so as to support the whole weight of the armature; by twisting
or untwisting the stem E any intensity of antagonistic force may be produced to
bring back the armature.
Figure VI. represents the frictionless armature (the spring pivots, etc., being the
same as those already described, are not represented) of such a shape as will allow
of the direct action of the coils on the armature without the help of soft iron cores.
A is a polarized armature having its ends bent right and left in a Z shape; the ends
are penetrating about half way into the coils B, B₁; the central part of these coils is
sufficiently wide to afford easy motion to the armature without touching them.
C is a projecting piece used as contact maker; D, D' are the polarising magnets, the
action of the coils on the armature is symetrical, and in fact the very same
mechanically. speaking as the one first described, and hence needs no further
explanation besides mentioning that a current passing in the coils B, B¹, shall either
attract or repel the armature according to the direction of that current.
The practical working of such an armature by the direct action of the coils is
only possible on account of the very perfect mechanical contrivance which wastes
no appreciable portion of the power exerted by the current. Nevertheless this

page_text: armature is not so sensitive as those above described, worked by means of soft iron
cores, but on the other hand it works very rapidly and with any variation of current
intensity above the least one that starts it at signalling speed, and there being no
remanent magnetism to be feared this style of frictionless armature never "sticks."
The frictionless armature used in connection with polarised instruments in which
the armature only is polarised has to be placed between two soft iron pieces A, A¹,
Fig. VII., in order to avoid the attraction of the cores B, B¹, which otherwise
would have to be counteracted by excessive twisting of the spring. The pieces
A, A¹, are connected with each other by a cross piece bridge pivoted about its
centre, and therefore when one piece of soft iron is moved for adjustment the other
also is displaced in the same degree.
If it be desired to employ the frictionless armature in such instruments that bring
back the armature by means of magnetism, either the soft iron pieces A, A¹, are
replaced by magnet poles having the same polarity, and connected so as to be
adjustable just as the soft iron pieces A, A¹, or the coils and cores have to be
duplicated, and then the general disposition of the instrument is shown in
Fig. VIII. S, S, S, are four shoes polarised by means of a magnet applied to a
common core plate; the free end of the magnet polarises the tongue or armature
N¹, N. In this case the central spring has only to support the weight of the
armature; the slight twist it receives during the motion of the armature is however
useful to a small extent in countercting the excess of magnetism remaining in the
attracting poles after the current has ceased. Figs. VII. & VIII. for clearness sake
show the coils, armature, &c., inverted.
The further adaptation of the frictionless and beamless armature to such instru-
ments as inkwriters, electric bells, etc., always remain the same in the general
mechanical disposition, except perhaps in some specific details, unimportant and
irrelative to the nature of the Invention.
Figure IX. represents the frictionless spring suspended armature to be used in
connection with sounders, and therefore where it has to produce as loud a sound as
possible the armature is prolonged on one or both sides a good deal beyond the
electro-magnet cores; one of its ends strikes on the platinum points, and it is
furnished with translation spring or platinum button. This armature answers well
for local circuits, as in this case the weight of the armature may be overlooked.
Figure X. represents the same armature, also producing a high sound, about once
as light as the former, but also once as costly to manufacture. It is well adapted for
direct working sounders on rather long lines; here lightness being of greater
importance sets aside the consideration of cost. The "sounding pipe" consists of a
metallic split pipe concentrical with the armature, and separated from it by an
annular empty space. The pipe A is fixed to the end of the armature by one of its
ends, as represented in the Figure at a, the other end is free and strikes against the
platinum points limiting its motion; this end may be furnished with platinum or
translation springs.
The advantage of a pipe over a solid piece is that it produces a much higher and
louder note for a given intensity of the impelling force of electro-magnet. Where
it is not objectionable on account of size the split "sounding pipe" is prolonged
right and left out of the armature, as in Figure XI.; it is then fixed to the armature
as already stated, and has a part projecting beyond the joint, or it is connected
to the armature about its central part a, Figure XI.
The only condition for success with regard to the sound produced is that where
the sounding pipe touches the armature the joint must be perfect; the slightest play
at that part reduces considerably the intensity of sound. Soldering the pipe to the
armature answers very well, and stout tinned sheet (not annealed) is a good material
for making such a pipe.
Having now described and particularly ascertained the nature of the said Inven-
tion, as communicated to me by my foreign correspondent, I would observe in
conclusion that any particular telegraphic instrument is not claimed, the Invention
being on the contrary of a complimentary nature to existing telegraphic instruments,

page_text: and its purport restricted to the new or improved combination of the spring
suspended frictionless armature set crosswise between the poles of an electro-magnet
or between coil poles, this armature being or not being furnished with a sounding
pipe, and to the spring suspended armature alone, whether flat or round, rectilineal
or Z shaped, and also with or without a sounding pipe, which said electro-magnet
and armature or armature alone are to be used as improved parts of telegraphic
instruments now in use. What is considered to be novel and original, and therefore
claimed as the Invention secured to me by the herein-before in part recited Letters
Patent is,
First. The frictionless or practically frictionless armature rendered frictionless at
the bearing of its axle by means of a pair or pairs of springs, or of a single central
spring supporting the weight of the armature and axle, substantially as described
with reference to the appended Sheet of Drawings.
Second. The disposition or combination of an armature round or flat, solid or
hollow, pivoted about its centre of gravity, and placed crosswise between the
poles of an electro-magnet or magnets, or again crosswise between coil poles, sub-
stantially as described and shewn on the Drawings hereunto annexed.
Third. The frictionless armature having its ends bent right and left into the
shape of a Z, so as to penetrate into the central parts of coils, substantially as
described with reference to Figure 6 of the accompanying Drawings.
Fourth. Increasing the sound produced in sounders by causing the crosswise set
or frictionless armature prolonged or furnished with a concentrical special split pipe,
as described, to strike against the studs limiting its play.
In witness whereof, I, the said Saint John Vincent Day, have hereunto set
my hand and seal, this Twentieth day of March, One thousand eight hundred
and seventy-seven.
ST. JOHN VINCENT DAY. (L.S.)