IMPROVED METHODS FOR DEVELOPING POWERFUL ELECTRICAL CURRENTS AND DISCHARGES PRINCIPALLY APPLICABLE TO THE PRODUCTION OF LIGHTS AT SEA, AND IN APPARATUS FOR DETERMINING ELECTRICAL RESISTANCES IN CONNECTION WITH SUCH AND OTHER CURRENTS
Year: 1867

page_text: LETTERS PATENT to Charles William-Siemens, of No. 3, Great George
Street, Westminster, in the County of Middlesex, for the Invention of
"IMPROVED METHODS FOR DEVELOPING POWERFUL ELECTRICAL CURRENTS AND
DISCHARGES PRINCIPALLY APPLICABLE TO THE PRODUCTION OF LIGHTS AT SEA,
AND IN APPARATUS FOR DETERMINING ELECTRICAL RESISTANCES IN CONNECTION
WITH SUCH AND OTHER CURRENTS."-Partly a communication from abroad
by Dr. Werner Siemens, of Berlin, Kingdom of Prussia.
Sealed the 30th July 1867, and dated the 31st January 1867.
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents, with his Petition, on the
31st January 1867.
I, CHARLES WILLIAM SIEMENS, of No. 3, Great George Street, Westminster
in the County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVED METHODS FOR DEVELOPING POWERFUL ELECTRICAL CURRENTS AND
DISCHARGES PRINCIPALLY APPLICABLE TO THE PRODUCTION OF LIGHTS AT SEA, AND
IN APPARATUS FOR DETERMINING ELECTRICAL RESISTANCE IN CONNECTION WITH SUCH
OTHER CURBENTS," to be as follows:
1
Lighthouses have in some cases been illuminated by means of electric
lamps which have the advantage of affording a much more intense light than
the ordinary oil lamps. As the powerful batteries, such as would be requisite
for these electric lamps, are exceedingly perishable and expensive to maintain

page_text: magneto-electrical machines have been employed for producing the requisite
electric currents; but even these machines are apt to lose their efficacy,
owing to a gradual decrease of the permanent magnetism of the steel bars
employed.
44
"
Now the present Invention consists, firstly, in obtaining powerful electric
currents applicable for illuminating lighthouses and for other purposes without
the aid either of large batteries or of permanent magnets by the following
method: A moveable keeper or armature of soft iron surrounded with a coil
of insulated wire is arranged in front of the poles of an electro-magnet, or of
electro-magnets, consisting likewise of soft iron bars surrounded with insulated
wire. The apparatus is provided with. a commutator operating in a
precisely similar manner to the arrangement for reversing currents usually
adopted in electro-magnetic motive-power machines. Rotary motion is
imparted to the armature in the opposite direction to that in which it would
move consequent on an electric current passing through the electro-magnets;
this motion of itself will produce no electrical effect, but if during such
rotation a magnetic impulse be imparted to the electro-magnetic arrangement
employed, either by the momentary insertion of a galvanic battery, however
small, into the system, or by a touch from a permanent magnet, or by dipping
the iron bars of the apparatus in a direction parallel with the earth's magnetic
axis an increase of the mechanical resistance of the rotating armature will
at once be perceptible which will steadily and rapidly augment until it reaches
a maximum regulated by the rapidity of rotation; at the same time a
proportionately increasing electric current will be developed in the coils,
which current is then passed through an electric circuit to any distant point,
either for producing light, as before stated, or for any other purpose to which
electric currents are applicable. If the rotary motion of the armature is
arrested the current will immediately cease, and if in recommencing such
motion an electric or magnetic impulse of an opposite kind to that first
imparted is communicated an electric current of the opposite nature to that
first produced will be generated in the circuit. For reproducing a current
in the same direction as the first after the rotation has been arrested it will
however not be found necessary every time to impart a fresh magnetic
impulse, because the residuary magnetism in the iron will suffice to commence
the inductive action. The form of rotating keeper or armature which 1
prefer to employ is that described in my Provisional Specification bearing
date the 10th September 1856, No. 2107, and which is particularly well
suited for the production of very powerful currents, such as are generated
by the before-described method, the strength of which currents is only limited

page_text: by the speed with which the armature can be made to revolve, and by the
conducting power of the wire of the circuit, these currents being capable of
attaining such a strength as to raise the temperature of the wire to that of a
red heat. Besides illuminating lighthouses it is also frequently desirable
to provide lights on beacons and buoys at sea, such beacons or buoys are
however in most cases placed in such inaccessible situations among rocks
or shoals that the employment of electric or other lamps for this purpose.
would be impossible, as these could not be properly attended to in rough
weather. The only possible means for providing such a light would be to
place an electric battery or other apparatus upon the land, and to connect
the beacons or buoys therewith by means of submarine cables. The employ-
ment of a lamp being inadmissible the light might be produced by electric
discharges or sparks generated by a Ruhmkorff coil between metallic points
suitably displayed behind reflectors. Even in this arrangemént, however,
a serious difficulty would arise in consequence of the condensing action of
submarine cables, the result of which would be that an electric discharge,
however powerful would not flowthrough the metallic conductor and discharge
itself at the point of severance, but would absorbed in charging the cable..
If it should be thought possible to place the Ruhmkorff coil upon the beacon
in order to transmit only the primary current from the land battery through
the cable it would be found that the same inductive action of the cable
would weaken the primary current to such an extent as to viciate the action
of the coil.
"Now my Invention- in this respect consists in the employment of the
extra current for the lighting of beacons or buoys. For this purpose I place
an apparatus, as before described, for the production of currents upon land,
and I connect the same by means of a submarine cable to the object 'to be
lighted; on the latter I place a heavy electro-magnet, the coils of which are
permanently connected to the cable. The current having traversed the cable
and the coil passes to the earth through a metallic contact piece, which piece
is connected to the moveable armature of the electro-magnet in such a manner
that as soon as a sufficient amount of magnetism has accumulated to cause
the armature to be attracted the metallic circuit is broken and a spark ensues
between the severed points; the power of this spark depends chiefly upon the
power and construction of the electro-magnet employed, which must be such
as to be powerful and at the same time capable of rapid magnetic discharge.
The charge of the cable is in this case no detriment, but aids, on the contrary;
n the power of discharge. When the discharge has taken place the armature
alls back and the metallic circuit is again established in order that the current

page_text: may again excite the electro-magnet and another luminous discharge be
effected; but instead of maintaining a continuous discharge of flashing lights
I. prefer to regulate their succession by establishing upon land any suitable
known clockwork arrangement: to interrupt and re-establish the circuit.
periodically; these périodical interruptions may be made serviceable for
enabling navigators to distinguish the several beacons and buoys of different
localities. One of the herein-before described apparatus for the production
of currents, or one galvanic battery, may be employed on land for the pro-
duction of flashing lights upon several buoys or beacons. In order to insure
metallic contact at the point where the light is produced I prefer to dip the
moveable contact point into mercury, which mercury I cause to circulate by
means of an agitator or pump receiving its motion from the electro-magnet,
or by gravitation, or otherwise, the object being to establish a supply of
metallic mercury at the point of contact; this point may be surrounded by
reflectors of the ordinary description for directing the light.
In cases where one current-producing machine or one galvanic battery is
made to provide the currents for several lighthouses, beacons, and buoys it is
necessary to regulate the electrical resistance of each cable, together with its
coil and apparatus, in such manner that each branch or circuit receives its due
proportion of electric charge from the common source of power. For this
purpose variable electrical resistances should be inserted at the battery station
into all or part of the circuits, to regulate which a ready means should be
provided to determine the resistance of each cable, coil, and connections, all
of which are liable to change through leakages or imperfect contacts and
connections. The apparatus usually employed for such purposes is the Wheat-
stone diagram, which, although suitable in other respects, is too complex a
machine and too difficult to understand for common usage in the hands of
persons who are not trained electricians. In order to obviate any difficulty on
this head I have constructed an apparatus by which the resistance of an
electric circuit may be read upon a scale in units of resistance by simply
moving a slide to such a point that the hand of an electrical detector or needie
points to its zero; for this purpose I place two coils of insulated wire opposite
to each other upon a sliding piece or segment of a circle, and I suspend
between them a small magnetic bar or needle. Both of these coils are con-
nected to the poles of one and the same battery, but the one branch includes
the circuit of which the resistance is to be measured, and the other comprises
simply a permanent resistance composed of the wire forming one of the coils,
and any additional resistance which may have to be added in the first
instance, in order to bring about a balance of effect upon the needle between

page_text: the two coils when the resistance to be measured is of the average magnitude,
and when the two coils are equidistant from the needle. If the resistance
to be measured exceeds the assumed average the slide carrying the two coils
will have to be moved a certain distance in such a direction as to approach
the one coil which is in connection with the increased resistance towards the
needle, while the second coil is made at the same time to recede from the
same needle in order to maintain the balance of effect between the coils upon
the needle. If, on the other hand, a smaller resistance has to be measured
than the assumed average the coils will have to be moved in the opposite
direction in order to re-establish the required balance. This motion of the
slide may be effected directly by means of an endless screw or otherwise, and a
table may be provided from which the amount of electrical résistance may be
read off for every position of the slide; or the table in question may be dis-
pensed with by making the slide carrying the coils abutt against the curvi
linear surface of a second slide, which curvilinear surface is so formed that
equal effects upon the needle are produced bymoving this second slide through
equal distances; the divisions upon this second slide will in this case directly
represent conventional units of resistance.
SPECIFICATION in pursuance of the conditions of the Letters Patent; filed
by the said Charles William Siemens in the Great Seal Patent Office on
the 31st July 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WILLIAM SIEMENS, of No. 3, Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirty-first day of January, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her reign
did, for Herself, Her heirs and successors, give and grant unto me, the said
Charles William Siemens, Her special licence that I, the said Charles
William Siemens, my executors, administrators, and assigns, or such other's
as I, the said Charles Williain Siemens, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVED METHODS FOR DEVELOPING POWERFUL ELECTRICAL CURRENTS AND

page_text: DISCHARGES PRINCIPALLY APPLICABLE TO THE PRODUCTION OF LIGHTS AT SEA, AND
IN APPARATUS FOR DETERMINING ELECTRICAL RESISTANCES IN CONNECTION WITH SUCH
AND OTHER CURRENTS," partly a communication to me from abroad by Dr.
Werner Siemens, of Berlin, Kingdom of Prussia, and partly of an Invention
and discovery made by myself, upon the condition (amongst others) that I, the
said Charles William Siemens, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE that I, the said Charles William Siemens, do hereby
declare the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and bythe following
statement thereof, reference being had to the accompanying Drawings and
to the figures and letters marked thereon, that is to say :-
The first part of this Invention consists in obtaining powerful electric
currents applicable for illuminating lighthouses and for other purposes without
the aid either of large batteries or of permanent magnets by the following
method A moveable keeper or armature of soft iron surrounded with a
coil of insulated wire is arranged in front of the poles of an electro-magnet,
or of electro-magnets, consisting likewise of soft iron bars surrounded with
insulated wire. The apparatus is provided with a "commutator "operating
in a preciselysimilar manner to the arrangement for reversing currents usually
adopted in electro-magnetic motive-power machines Rotarymotion is imparted
to the armature in the opposite direction to that in which it would move con-
sequent on an electric current passingthrough the electro-magnets ;this motion
of itself will produce no electrical effect, but if during such rotation a magnetic
impulse be imparted to the electro-magnetic arrangement employed either
by the momentary insertion of a galvanic battery, however small, into the
system, or by a touch from a permanent magnet, or by dipping the iron bars
of the apparatus in a direction parallel with the earth's magnetic axis, an
increase of the mechanical resistance of the rotating armature will at once
be perceptible, which will steadily and rapidly augment until it reaches a
maximum regulated by the rapidity of rotation. At the same time a pro-
portionately increasing electric current will be developed in the coils, which
current is then passed through an electric circuit to any distant point; either
for producing light as before stated or for any other purpose to which electric
currents are applicable. If the rotary motion of the armature is arrested

page_text: the current will immediately. cease, and if in recommencing such motion an
electric or magnetic impulse, of an opposite kind to that. first imparted is
communicated an electric current of the opposite nature to that first' produced
will be generated in the circuit. For re-producing a current in the same
direction as the first after the rotation has been arrested it will, however, not
be found necessary every time. to impart a fresh magnetic impulse, because
the residuary magnetism in the iron will suffice to commence the inductive
action..
The form of rotating keeper or armature which I prefer to employ is that
described in my Provisional Specification, bearing date the Tenth September
1856, No. 2107, and which is. particularly well suited for the production
of very powerful currents, such as are generated by the before described
method, the strength of which currents is only limited by the speed with which
the armature can be made to revolve, and by the conducting power of the
wire of the circuit, these currents being capable of attaining such a strengthi
as to raise the temperature of the wire to that of a red heat.
Figures 1 to 5, on Sheet I. of the accompanying Drawings, shew one
arrangement of apparatus for carrying this part of the Invention into effect;
Figure 1 shews a side elevation of the apparatus; Figure 2 shews an end
elevation; Figure 3 shews a plan; Figure 4 shews a transverse-section of the
arinature; and Figure 5 shews a diagram explanatory of the direction of the
currents through the apparatus..
A', A3, A3, A', are soft iron bars forming together with the connecting
plate B and the coils C1,C2,C3,C+, two horse-shoe electro-magnets, between the
poles. of which is the revolving cylindrical armature D of the form previously
referred to, namely, having deep longitudinal grooves in which is wound a
coil E, as shewn in the transverse section at Figure 4; the spindle F of
this armature is carried in bearings. G, G, G, and is provided with a pulley H,
whereby rotary motion is imparted to it by means of a strap H' from any
suitable source of motive power. The other end of the spindle forms together
with the contact springs I, I, a commutator for changing the currents in
the armature coil as it revolves; the spindle is for this purpose cut in half
longitudinally, the part F' being separated from F by the interposition of
insulating material between them, the two parts are kept together in position
by the rings of insulating material, and set screws J, J; the part F' is in
metallic connection with the one end of the armature coil E, while the part F³
is put in connection with the other end thereof by means of the insulated
wire K passing through a hole in the spindle F; the contact springs I', I³,
are carried, by brackets L, L, separately fixed to an insulated block M,

page_text: and having springs and screws, as shewn, for adjusting the pressure of the
springs I', I; the brackets L', L, and consequently the springs 1', I², are
put in metallic connection with the coils of the electro-magnets in the following
manner: The connecting piece B carries a plate of insulating material N
upon which are fixed four mercury cups O', 0, 0, 0, with which the one end
of the coils C, C³, C3, C4, are respectively in metallic connection as shewn in
plan, while the other end of the coil C is connected to that of C and that
of C to C; the bracket L', and consequently the one end of the armature
coil is put in metallic connection with the cup O' by means of the wire P¹,
while the bracket L, and with it the other end of the armature coil is put in
metallic connection with the cup O' by means of the wire Ps. From this
arrangement it will be seen that if a metallic connection be established
between the cups O' and O³, and between Os and O', any current passing from
the pole I' of the armature coil will at O' be divided in two, one portion
passing successively through the coils C' and C, and thence to the cup O',
while simultaneously the other portion of the current passes through the
coils C and C+ to the cup O', whence the joined currents pass through the
wire 1 to the pole L of the armature coil. If, on the other hand, a metallic
connection be established merely between the cups 0 and O³ then the
current from L' will pass first through the coils C and C2 consecutively, and
then passing from the cup 0 to 0³ it will pass consecutively through the
coils C and C+, and thence as before through the cup O' back to the pole L.
By the first-described or parallel action of the coils quantity currents are
obtained, while by the last-described or consecutive action intensity currents
are obtained. The diagram at Figure 5 will more clearly indicate the direction
of the currents in each case, the dotted lines o¹, 03, shewing the metallic con-
nection for the parallel arrangement, while the dotted line o³ shows the
connection for the consecutive arrangement. Thus in the first case the current
starting from the one pole of the armature coil E passes through P¹ to O'
thence consecutively through C and C, and through 0 to 0, while at the
same time it passes through o¹ to 0, and thence consecutively through C3,
and C to O', whence the joined currents pass through P2, and through
the circuit X interposed at this or at any other point to the other pole of
the coil E.
Assuming now that a small amount of residuary magnetism exists in the
electro-magnets A1, A2, A3, A', and the armature D, and that the latter be
caused to rotate in the reverse direction to that in which it would move in
consequence of the attraction of the electro-magnets, that is to say, so as to
cause like named poles to approach and dissimilar poles to be severed, ther

page_text: an increase of magnetic tension will be produced inducing alternately reversed
electric currents in the armature coil E, which is being passed in the same
direction by the commutator into the coils C of the electro-magnets will
induce a proportionately increased magnetism in the latter; this will again
induce stronger currents in the armature coil, and thus a reciprocal action will
take place, whereby the strength of the electric current in the coils and in any
circuit in connection therewith will be rapidly increased until a maximum is
attained, which is determined by the capacity of the electro-magnets and the
speed at which the armature may be made to rotate, the resistance to such
rotation being, of course, increased in the same ratio as the strength of the
current increases.
Although the form of armature, above described, is particularly suited for
producing very powerful currents, yet it has the disadvantage of becoming
very much heated by the rapid change of its polarity; this disadvantage is
obviated in the arrangement of the apparatus shown at Figures 6 to 8 on
Sheet 1. of the Drawings; Figure 6 shews a plan of the apparatus, Figure 7
shews a transverse section, and Figure 8 shews a diagram indicating the
manner in which the electric current is established in the coils and conducted
through the circuit. In this arrangement a number of coils C, C, C, wound
on reels R are arranged in a circle, and a curved bar of soft iron D, or which
in this case may be made of steel, constituting the electro-magnet, terminating
at S and N, and forming together with the piece of brass Q inserted between
its poles a complete circle; is arranged to revolve easily through central holes
in the reels, the ring being for this purpose supported by three grooved rollers
S and caused to revolve by means of a cord T passed round in the groove d
on its outer circumference; the one end of all the coils C are in inetallic con-
nection with the central pillar L', while the outer rings are capable of being
put in like metallic connection with the ring L2 by the following arrange-
ment-The ends of the coils are connected to the screws U fixed in the block
of insulating material V; these screws are in metallic contact with a cor-
responding number of springs I, I, the one end of each of which is also held
by the insulating block V, while the other ends thereof when touching the
ends of the screws W establish a metallic contact between the screws U, and
therefore the coils C and the ring L2; such contact is, however, prevented in
all the coils excepting those four, which are for the time being nearest the
north pole of the electro-magnet by means of a corresponding number of bell-
crank levers Z, which are pressed downwards so as to depress the springs I
by a projecting steel fillet a formed round the inner circumference of the
electro-magnet D, excepting at that part nearest the north pole of the

page_text: magnet; the four bell cranks at such part are consequently pressed up by
springs b so as to allow of the contact between the springs I and the screws W.
The pillar L' is carried by the insulating block V, and passes through the
same and the base plate C, beneath which it is provided with an insulated
screw cup d; the ring L, which is also insulated, is secured by insulated
screws e passing through the plate c, one of which screws is connected by a
wire to the screw cup g, shewn on plan, while a second wire connects the
screw cup of the pillar L' to the screw cup 2, and therefore by connecting
the screw cups and i the circuit is completed. The Diagram at Figure S
shews the direction of the circuit more clearly; D is the electro-magnet; Q,
the brass connecting piece; C, C, are the coils; L' is the central pillar, to
which the ends of all the coils are connected; L2 and W are the contact ring
and screws, and the lines 1, 1, represent the contact springs connected to the
other ends of the coil. It will be seen that only the four coils nearest the
north poles of the electro-magnet are in connection with the ring L². Any
currents generated in these four coils will consequently pass from the ends l'
thereof to the central pillar where they join, the combined current passing
thence through the wire to the screw cup i, thence through any circuit X
that may be interposed to the screw cup g, from which it passes through the
wire f, contact ring L³, and springs I, back to the other ends of the coils,
thus completing the circuit. If now a current be generated in these coils by
the momentary introduction of a battery into the circuit, a corresponding
polarity will be induced in the electro-magnet D, and if this be now caused to
revolve by the cord T in the reverse direction to that in which would be
attracted by the coils currents will be generated in each of the other coils C
in succession. At every revolution the force of the electro-magnet will
increase, and this will in its turn effect a proportional increase in the strength
of the currents in the coils, which increasing reciprocal action will continue
until the maximum magnetic force that the electro-magnet is capable of has
been attained. The current generated in the above-described manner may,
as before stated, be employed either for producing light or for inducing similar
currents in other electro-magnetic apparatus, or for any other purposes to
which electric currents are applicable. Besides illuminating lighthouses it is
also frequently desirable to provide lights on beacons and buoys at sea, such
beacons or buoys are, however, in most cases placed in such inaccessible
situations among rocks or shoals that the employment of electic or other
lamps for this purpose would be impossible, as these could not be properly
attended to in rough weather. The only possible means for providing such a
light would be to place an electric battery or other apparatus upon the land,

page_text: and to connect the beacons or buoys therewith by means of submarine cables;
the employment of a lamp being inadmissible on account of the attention
required in working it, the light might be produced by electric discharges or
sparks generated by a Ruhmkorff coil between metallic points suitably dis-
played behind reflectors. Even in this arrangement, however, a serious
difficulty would arise in consequence of the condensing action of submarine
cables, the result of which would be that an electric discharge, however
powerful, would not flow through the metallic conductor and discharge itself
at the point of severance, but would be absorbed in charging the cable. If
it should be thought possible to place the Ruhmkorff coil upon the beacon
in order to transmit only the primary current from the land battery through
the cable it would be found that the same inductive action of the cable
would weaken the primary current to such an extent as to vitiate the action of
the coil.
Now my Invention in this respect consists in the employment of the extra
current for the lighting of beacons or buoys. For this purpose I place an
apparatus as before described for the production of currents upon land, and I
connect the same by means of a submarine cable to the object to be lighted;
on the latter I place a heavy electro-magnet, the coils of which are perma-
nently connected to the cable. The current having traversed the cable and the
coil, passes to the earth through a metallic contact piece, which piece is con-
nected to the moveable armature of the electro-magnet in such a manner that
as soon as a sufficient amount of magnetism has accumulated to cause the
armature to be attracted the metallic circuit is broken and a spark ensues
between the severed joints. The power of this spark depends chiefly upon the
power and construction of the electro-magnet employed, which must be such
as to be powerful and at the same time capable of rapid magnetic discharge.
The charge of the cable is in this case no detriment, but aids, on the contrary,
in the power of discharge; when the discharge has taken place the armature
falls back and the metallic circuit is again established in order that the current
may again excite the electro-magnet, and another luminous discharge he
effected; but instead of maintaining a continuous discharge of flashing lights I
prefer to regulate their succession byestablishing upon land anysuitable known
clockwork arrangement to intercept and re-establish the circuit periodically;
these periodical interruptions maybe made serviceable for enabling navigators
to distinguish the several beacons and buoys of different localities. One of
the herein-before described apparatus for the production of currents or one
galvanic battery may be employed on land for the production of flashing
lights upon several buoys or beacons. In order to insure metallic contact at

page_text: the point where the light is produced I prefer to dip the moveable contact
point into mercury, which mercury I cause to circulate by means of an agitator
or pump, receiving its motion from the electro-magnet, or by gravitation, or
otherwise, the object being to establish a supply of metallic mercury at the
point of contact; this point may be surrounded by reflectors of the ordinary
description for directing the light.
Figures 9 to 11 on Sheet II. of the accompanying Drawings show the just
described apparatus for producing light by electrical discharges; Figure 91
shows a side elevation of the same, partly in section; Figures 10. shows a
plan; and Figure 11 shows an enlarged sectional elevation of the mercury
pump.
A, A, is a powerful electro-magnet, the one end of the coils round which is
in connection through a cable with the one pole of the current producer or
battery, while the other end is in metallic connectionwith the mercurytrough B
a lever C, the fulcrum of which is carried by the pillar D, establishing a con-
nection through the earth with the other pole of the battery carries at one
end the armature E to the electro-magnets, and is provided at the other end
with a screw F; this end of the lever is loaded with weights G, so that when
the armature E is not attracted by the electro-magnets, the screw F dips into
the mercury trough and thus establishes the electrical circuit. When by the
passage of the currents through the electro-magnets these have become suffi-
ciently powerful to attract the armature this in moving down raises the
screw F out of the mercury, and thus interrupts the circuit, whereupon a
flash of light produced by the return current will pass from the mercury
trough B to the screw F. The current being intercepted the power of the
electro-magnets will cease, and consequently the weights G will cause that
end of the lever to move down and to re-establish the circuit by the screw F
dipping into the mercury again. In order to insure a constant metallic
surface to the mercury in the trough it is constantly renewed therein in the
following manner: A small force pump H, having double inlet valves I, I,
and outlet valves J, J,, to insure perfect action is situated inside a closed insu-
lated reservoir K containing mercury. The rod T to the piston L of the
pump is attached by an insulated connection to the lever C, so that as this
moves up and down as before described it draws mercury into the
pump and
then forces it through the pipe M into the passage N, whence it flows over
into the trough B, from which it falls into the passage O, conducting it back
into the reservoir K. S is a piece of india-rubber tubing secured over the
open end of the pump and to the piston rod T, so as to act as a stuffing box.
The contact points F and B are surrounded by any suitable arrangement of

page_text: prisms or reflectors P for conveying the light produced to a distance. In
order to equalize the motion of the lever C the end thereof is connected to a
small piston Q, having a small hole through it, which is caused by the motion
of the piston to move up and down in the closed cylinder R filled with oil or
other fluid, which fluid is caused by the motion of the piston to pass from the
one side to the other through the small hole thereof. The electro-magnets A
are enclosed in a casing U containing paraffin or other suitable substance for
protecting them against exposure to the weather. As before stated it is
preferred to interrupt the succession of electrical discharges of the above
described apparatus periodically by means of clockwork mechanism. The
arrangement of the mechanismwhich I prefer to employ is shown at Figures 16
and 17 on Sheet III. of the accompanying Drawings.
Figure 16 shews a sectional elevation of the same, and Figure 17 shews a
plan. A', A2, are two levers working on separate and insulated fulcra at B';
the front ends of both levers are provided with a rod C', C, dipping into the
mercury cup D', while the other ends thereof are caused by springs not shown
on the Drawing to rest upon two cams E', E2, made to revolve slowly in the
direction of the arrow by the clockwork mechanism of any suitable known
construction in the casing F'. The lever A' is in metallic contact with
the cam E', and through it and the casing F' with the wire G₁ connected to
one pole of the battery or current producer in the circuit. The contact point
of the lever A, on the other hand, is of insulating material, and the lever is
therefore not in metallic connection with the wire G', but is put in metallic
connection with the other pole of the battery or current producer by the
wire H. From this arrangement it will be seen that while the rods C', 09,
both dip into the mercury cup D' the current passes from the one pole of the
battery, say, through the wire G', case F', lever A', and mercury cup D' to
the lever A, and thence through the wire H' and the circuit to the other pole
of the battery, and so long as the current passes in this manner electrical
discharges will take place at the illuminating apparatus, as before described.
When, however, the beak of the cam E¹ arrives in its highest position the end
of the lever A will fall suddenly from it on to the lowest part of the cam
whereby the rod C¹ will be made to rise suddenly out of the mercury cup, and
the circuit will consequently be suddenly broken until by the revolution of the
cam the rod C is again moved down into the mercury. On the other hand
the rod C² of the lever A2 will be gradually raised out of the mercury, so as to
break the circuit by the action of the cam E in its motion towards the lowest
position, and when the beak has arrived at the lowest point the lever A will
suddenly fall on to the lowest part of the cam and cause the rod C³ to move

page_text: suddenly down into the mercury, and thus to establish the circuit. From
this arrangement it will be seen that the circuit is twice broken and closed
during one revolution of the cams, while by causing the motion of the rods
into and out of the mercury to take place suddenly during two of these
operations the mercury will not so soon become oxydized by the passing of
sparks as would otherwise be the case. The arrangement of the circuit in
connection with this and the light producing apparatus will be seen more
clearly from the diagram at Figure 18. The current passes from the one
pole of the battery at X through the wire a and cable 6 to the coils of the
magnet A, thence through the mercury cup B, contact point F, wire c, and
earth to wire H', from which it passes through the contact lever A³, mercury
cup D', contact lever A', clockwork case F', and wire G¹ to the other pole of
the battery. Several beacon lights may be worked by the same source of
electricity, but in order that they may be readily distinguished the one from
the other I prefer to open and close each circuit by a separate contact
arrangement of distinctive periods for making and breaking contacts, or the
periods may be varied at will in order to convey conventional signals to the
shipping out at sea. In cases where one current producing machine or one
galvanic battery is made to provide the currents for several lighthouses,
beacons, and buoys, it is necessary to regulate the electrical resistance of each
cable together with its coil and apparatus in such manner that each branch or
circuit receives its due proportion of electric charge from the common source
of power. For this purpose variable electrical resistances should be inserted
at the battery station into all or part of the circuits, to regulate which a ready
means should beprovided todeterminethe resistance of each cable, coil, andcon-
nections, all of which areliableto change through leakages or imperfectcontacts
and connections. The apparatus usually employed for such purposes is the
Wheatstone diagram, which although suitable in other respects, is too complex
a machine and too difficult to understand for common usage in the hands of
persons who are not trained electricians. In order to obviate any difficulty on
this head I have constructed an apparatus by which the resistance of an
electric circuit may be read upon a scale in units of resistance by simply
moving a slide to such a point that the hand of an electrical detector or needle
points to its zero, for this purpose I place two coils of insulated wire opposite
to each other upon a sliding piece or segment of a circle, and I suspend
between them a small magnetic bar or needle; both of these coils are
connected to the poles of one and the same battery, but the one branch
includes the circuit of which the resistance is to be measured, and the other
comprises simply a permanent resistance composed of the wire forming one of

page_text: the coils, and any additional resistance which may have to be added in the
first instance in order to bring about a balance of effect upon the needle
between the two coils when the resistance to be measured is of the average
magnitude, and when the two coils are equidistant from the needle; if the
resistance to be measured exceeds the assumed average the slide carrying the
two coils will have to be moved a certain distance in such a direction as to
approach the one coil which is in connection with the increased resistance
towards the needle, while the second coil is made at the same time to recede
from the same needle in order to maintain the balance of effect between the
coils upon the needle; if on the other hand a smaller resistance has to be
measured than the assumed average, the coils will have to be moved in the
opposite direction in order to re-establish the required balance. This motion
of the slide may be effected directly by means of an endless screw or other-
wise, and a table may be provided from which the amount of electrical
resistance may be read off for every position of the slide, or the table in
question may be dispensed with by making the slide carrying the coils abut
against the curvilinear surface of a second slide, which curvilinear surface is
so formed that equal effects upon the needle are produced by moving this
second slide through equal distances; the divisions upon this second slide will
in this case directly represent conventional units of resistance.
Figures 12 to 15, on Sheet II. of the Drawings, shew the construction of an
apparatus arranged as last described. Figure 12 shews a plan of the same;
Figure 13 shews an end elevation partly in section; Figure 14 shews a longi-
tudinal section, and Figure 15 shews a diagram of the circuits.
From the top of the glass casing A is suspended a galvanometer needle B.
cach end of which is situated over a graduated arc C, C, the exact position of
the needle relative to such arcs being capable of adjustment by means of the
three screws D, D, D, acting upon the suspension rod E of the needle, as
shewn; upon the base of the instrument is a bar F, carried between guides G,
and capable of sliding backwards and forwards in a direction at right angles
to the needle. The bar has fixed upon it two reels I, I', carrying two coils of
insulated wire H, H', (the coil H is shewn removed on the Drawing) which
are both connected to the poles of a battery at Y, the circuit of the coil H
including however the circuit X, the unknown resistance of which is to be
measured, while the circuit of the coil H' includes a coil R of known resist-
ance. The connections of the coils to the battery Y and to the resistance
coils for this purpose are established as follows:-A stopper having been
introduced at K to close the circuit, the current passes from the one pole of
the battery Y to the screw J, thence through a wire L to the screw M, from

page_text: which it passes through the wire N (formed so as to allow of the motion
of the coils) to the coil H where the current divides, passing partly
through this coil and partly through the wire O to the coil H'. From the
other end of the coil H the current passes through the wire P to the screw Q,
thence through the wire 7 to the screw S, to which the one end of the circuit. X
of unknown resistance is connected, while the other end thereof is connected
to the screw T; the current consequently passes through such circuit to the
screw T, and thence through the wire U and screws V and W to the other
pole of the battery. On the other hand the current from the coil H' passes
through the wire a and screws b and c to the known resistance R, and thence
through the screw d and wire e to the wire U, where it joins the current
passing to the pole of the battery. The direction of these circuits will
be more clearly understood from the diagram at Figure 15, where Y is the
battery, H, H', are the coils, X, the unknown resistance, and R, the known
resistance, K is the stopper for completing the circuit. The end of the sliding
bar F rests with an agate point against the curved surface of a slide f, it
being kept against such surface so as to follow it as it advances or recedes by
means of the spring g attached to it and to the base of the apparatus. The
slide is made to move backwards and forwards in front of a graduated scale h
by means of a pinion i in gear with a toothed rack formed on the under sur-
face of the slide, and turned by means of the button j. It will be seen that if
the slide f is moved, say, to the left in Figure 12, the sliding bar F will move
so as to cause the coil H connected to the unknown resistance to approach
the needle B, and the other coil to recede therefrom; if, on the other hand,
the slide is moved in the other direction, the coil H will recede from and the
coil H' will approach the needle. In the first case therefore the effect of
the coil H upon the needle will be increased, and that of H' diminished,
while the last case the reverse will take place. Now, the curve of the
slide is so formed that equal effects are produced by the coils by moving the
slide through equal distances, and these effects may consequently be read off
in conventional units of resistance upon the equal divisions of the scale h, the
slide f being for this purpose provided with a vernier at k. The known
resistance R introduced into the circuit of the coil H' is of an average degree
in order that when a similar average resistance is introduced at X a balance
of effect of the coils upon the needle is established so as to cause it to point
to zero by bringing the slide f into a central position, in which case also the
coils will of course be situated equidistant from the needle. If now while
the coils and slide are in this position a greater unknown resistance be intro-
duced at X the effect of the coil H upon the needle will be diminished, and

page_text: the needle will move away from zero.
In order therefore to bring about a
balance of effect again it will be necessary to approach the coil H, and to
cause H' to recede, which is effected as before stated by moving the slide f
towards the left hand at Figure 12, whereby the exact number of units
of resistance of the circuit X above the average before indicated will be
read off the scale. If on the other hand a resistance below the average be
introduced at X the coil H will have to recede and H¹ to advance in order
to establish a balance of effect, and consequently the slide f will have to be
moved to the right, thus indicating upon the scale the exact number of units
of resistance of the circuit X below the average. In order to adjust the
needle accurately to zero point before commencing operations stoppers are
introduced at land m in order to short circuit the currents in both coils, and
thus render their resistances and effect upon the needle absolutely identical.
Having thus described the nature of the several parts of this Invention, and
the manner of performing the same, I wish it to be understood that I do not
limit myself to the precise arrangement of apparatus herein-before described
with reference to the accompanying Drawings, as these may obviously be
variously modified without departing from the nature of the said Invention;
but what I claim is,
First, developing powerful electric currents in electro-magnetic apparatus
by causing the poles of a rotating electro-magnet or keeper to be forcibly
approached successively to the similar poles, and forcibly severed from the
dissimilar poles of stationary electro-magnets or coils, the currents being
directed by means of a commutator or of current changers, so as to produce
the above effect, and thereby cause an accumulation of magnetism and of the
currents produced by the apparatus, substantially as herein-before described
with reference to Figures 1 to 8 on Sheet I. of the accompanying Drawings.
Second, employing the return or extra current produced in breaking an
electro-magnetic circuit for producing flashes of light through submarine
cables out at sea.
Third, the general arrangement of apparatus herein-before described with
reference to Figures 9 to 11 and 16 to 18 on Sheets II. and III. of the
accompanying Drawings, for producing electric flashes of light out at sea
through a submarine cable with automatic means provided for renewing the
mercury contact, and with appliances for regulating the periods of electrical
discharges.
Fourth, constructing apparatus for measuring electrical resistances in which
two insulated coils, both connected to one and the same battery, but one
including the resistance to be measured in its circuit are made the one to

page_text: advance to and the other simultaneously to recede from a galvanometer needle
suspended between the two in order to produce a balance of effect thereon,
the position of such coils when the equilibrium is established being made to
indicate the unknown resistance, substantially as herein-before described with
reference to Figures 12 to 15 on Sheet II. of the accompanying Drawings..
Fifth, effecting the motion of the coils of the said apparatus for measuring
electrical resistances by means of a curved slide, against which the bar carrying
the coils rests, and which slide in being moved in one direction or the other
for adjusting the coils indicates directly upon a scale the number of conven-
tional units of resistance in the resistance to be measured, the curved surface
of the slide being so formed that equal effects are produced by moving the
slide through equal distances, substantially as herein-before described with
reference to Figures 12 to 15 on Sheet IV. of the accompanying Drawings...
In witness whereof, I, the said Charles William Siemens have hereunto
set my hand and seal, this Thirty-first day of July, in the year of our
Lord One thousand eight hundred and sixty-seven.
Witness,.
C. D. ABEL,
20, Southampton Buildings.
C. W. SIEMENS. (L.S.)