IMPROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY
Year: 1857

page_text: LETTERS PATENT to Charles Weightman Harrison, of Woolwich, in the
County of Kent, Civil Engineer, for the Invention of "IMPROVEMENTS
IN OBTAINING LIGHT BY ELECTRICITY."
Sealed the 28th August 1857, and dated the 28th February 1857.
PROVISIONAL SPECIFICATION left by the said Charles Weightman
Harrison at the Office of the Commissioners of Patents, with his
Petition, on the 28th February 1857.
I CHARLES WEIGHTMAN HARRISON of Woolwich in the County of Kent,
Civil Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY," to be as follows:-
My Invention relates firstly to the preparation of electrodes.
It is well known that condensed gas carbon from its great purity and
density is the best and most durable form of charcoal for the display of
electric light.
Now one of my improvements under this head of my Invention consists
in placing pieces of metal or other material in gas retorts or in tubes
gas carbon.
connected therewith, for the purpose of receiving a deposit of
I allow the pieces to remain exposed to the action of the gas until they are
coated to a desired thickness and I then cut or grind them down to any
required form of electrode.

page_text: Another of my improvements under this head of my invention consists
in the use of electrodes of spongy or powdered metals prepared by means
of compression into any determinate shape or cut to a required form from
blocks or masses of such compressed metals. In the employment of these
electrodes I produce lights of various colors according to the kind of metal
or combination of metals used.
My Invention relates secondly to an arrangement of electrodes.
In every apparatus employed up to the present time it is necessary in
order to obtain a continuous light that the electrodes should approach
each other as fast as diminution takes place, but by my improvements this
necessity is obviated. I employ a cylindrical electrode and placing it on
an axis in the direction of its length, I impart to it by suitable arrange-
ments, a rotary as well as horizontal or onward motion in the line of its
axis. Opposite to the periphery or circumference of this electrode I place
another electrode and by preference I use one that is in the form of a point
or pencil, the apex being in contact with the circumference of the
cylindrical electrode and near to one of its ends. If motion be now given
as herein-before stated to the cylindrical electrode, the opposite electrode
will trace a spiral path over its surface from one end to the other, the
contiguity of the convolutions being determined by the rate of its onward
progression. In order to obtain the light I connect the opposite or
pointed electrode with the armature of an electro-magnet or with a coil of
conducting medium in such manner that on the transmission of a current
of electricity this electrode is drawn or moved away to a suitable distance
from the other and then retains a fixed position until on breaking the
electric circuit it again renews the contact. I form the circuit of the
current so as to render the rotary cylinder an electrode of positive
electricity, and the point or pencil an electrode of negative electricity.
The light being by these arrangements produced on the circumference of
the cylindrical electrode and its motion continuously bringing fresh
surface to the operation of the luminous portion of the current, an uniform
amount of resistance is offered to its passage and the light is generated
with a steady constancy due to that of the current itself.
The third part of my Invention relates to a mode of maintaining a very
uniform distance between a rotary disc positive electrode and a point or
pencil negative electrode. The said mode consisting principally in
keeping in contact with the periphery of a rotary disc electrode a roller
or pulley or other contrivance which is connected by a chain or band or by
levers with a pendant or sliding point or pencil electrode, whereby as the
positive electrode diminishes the negative electrode is permitted con-
tinuously to advance without causing-sudden fluctuations in the light.

page_text: The fourth part of my Invention refers to improvements in producing a
succession of flashes or streams of light.
It has already been proposed to obtain electric light by a rapid succes-
sion of flashes resulting from the vibration, produced by mechanical
agency, of electrodes. I do not therefore claim as new that which has
been done before but I adopt the use of one or more electro-magnets to
give rise to or effect a reciprocative or vibrative motion in electrodes. I
sometimes employ a steel armature in connection with the electro-magnets
so that its residual magnetism shall serve to retain the electrode or
electrodes in the position assumed during the passage of the last current.
On the arrival of each succeeding current, the transmission of which is
regulated by a suitable electrotome, the electrodes are moved away one
from another by the force originated by the current, a flash or stream of
light is produced and the residual magnetism holds the electrodes in
position for another electric impulse.
Another mode whereby I produce successive flashes or streams of light
consists in the employment of a coil of conducting medium, and by means
of an axial bar or magnet used in connection therewith a vibratory motion
is given on the passage of the current to one or more electrodes. In those
arrangements of electrodes where contact is made between them I prefer
to introduce therein a spring or some compressible body in such a
manner and position that it will break the force of concussion. In any
arrangement of a vibratory system of electrodes I.employ an electrotome
by which the current is so directed that it shall at every impulse impart
a negative nature to the vibrating electrode.
This part of my Invention is very suitable for lighting marine buoys,
the electricity being conveyed through insulated submarine conducting
medium.
The fifth part of my Invention relates to the introduction of an in-
ductive coil (formed either with or without a condensing arrangement) to
be used in connection with a primary current, and one of my improve-
ments herein consists in giving any required motion to electrodes by the
operation of the primary current and producing light by means of the
induced current alone.
The sixth part of my Invention consists in combining the current
generated in an inductive coil with a current of magneto-electricity pro-
duced by the motion of a conductor within the action of permanent
magnets.
The seventh part of my Invention consists in a peculiar mode of obtain-
ing the electric light by which signals are effected. It comprises the
application and use of an electrotome or an arrangement of electrotomes

page_text: by which the current shall be let on both at rapid and at long intervals,
or both at rapid, at short and at long intervals. At each passage of the
current a distinct flash of light is produced and this may be taken to
denote an unit, the short intervals the end of a number and the long inter-
vals to signify either the termination of the signal, as when a repetition
of it is desired, or the end of a combination of numbers. This system
may be made to represent words or sentences as well as numerals and
being easily understood it is well adapted to lighthouses.
il also propose to indicate to vessels by flashes of electric light the depth
of water in harbours or on banks, and to effect this by means of a float
within a tube, which, by suitable mechanical contrivances, as it rises and
falls calls into operation different electrotomes and these by completing
the circuit of the current give rise to flashes of light, in number according
to the depth of water in feet. To distinguish this from other marine lights
I make it a colored light by placing a colored glass before it, or by the use
of my improved metal electrodes described in the first part of this my
Provisional Specification.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Weightman Harrison in the Great Seal Patent
Office on the 28th August 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WEIGHTMAN HARRISON of Woolwich in the County of Kent Civil Engineer
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria by Her Letters
Patent bearing date the Twenty-eighth day of February in the year of our
Lord One thousand eight hundred and fifty-seven in the twentieth year
of Her reign did for Herself Her heirs and successors give and grant unto
me the said Charles Weightman Harrison Her special licence that I the
said Charles Weightman Harrison my executors administrators and
assigns or such others as I the said Charles Weightman Harrison my
executors administrators and assigns should at any time agree with and
nō 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 "IMPROVEMENTS IN OBTAINING
LIGHT BY ELECTRICITY" upon the condition (amongst others) that I the said
Charles Weightman Harrison my executors or administrators by an
instrument 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

page_text: 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 Weightman Harrison do
hereby declare the nature of my said Invention and in what manner the
same is to be performed to be particularly described and ascertained in
and by the following statement thereof reference, being had to the accom-
panying Drawings and to, the figures and letters. marked thereon that is to
say,
My said Invention relates firstly to the preparation of electrodes for
producing light.
It is well known that condensed gas carbon from its great purity and
density is the best and most durable form of charcoal for the display of
electric light.
Now one of my impropements under this head of my Invention consists
in placing pieces of metal or other material in gas retorts, or in tubes
connected therewith for the purpose of receiving a deposit of gas carbon.
1 form hollow cylinders of carbon or barrel electrodes by passing a current
of coal gas through a chamber which is traversed by metal tubes joined
with a furnace the flame and heated air of which are drawn through
the tubes. When these attain a red heat they gradually become coated
with a dense form of carbon. I form pencil or solid carbon electrodes by
suspending small rods.or pencils of wood charcoal upon a frame of iron,
which. I place within a heated gas chamber or retort, where it will be
subjected to a high degree of heat. By this process the charcoal is
rendered hard and lasting. I allow the tubes and pieces to remain ex-
posed to the action of the gas until they are coated to a desired thickness
and I then cut or grind them down to any required form of electrode.
Another of my improvements under. this head of my Invention consists
in the use of electrodes of spongy or powdered metals prepared by means
of compression into any determinate shape or cut to a required form from
blocks or masses of such compressed metals. I first slightly moisten the
metallic powder and having placed it in an iron mould of any suitable
shape, I apply hydraulic or other pressure to a piston which accurately
fits the aperture of the mould. In this way the pulverulent matter is
solidified and made suitable for use in electric light apparatus. In the
employment of these electrodes I produce lights of various colors accord-
ing to the kind of metal or combination of metals used. The metallic dust
may be mixed in various proportions with carbon or other substance. I
obtain a brilliant white light by using a positive electrode formed of a
combination of zinc powder and plumbago and consisting of three parts
of plumbago with one of zinc.

page_text: My Invention relates secondly to an arrangement of electrodes.
In
In every electric light apparatus employed up to the present time it is
necessary in order to obtain a continuous light that the electrodes should
approach each other as fast as diminution takes place, but by my improve-
ments this necessity is obviated. I employ a cylindrical electrode and
placing it on an axis in the direction of its length. I impart to it by
suitable arrangements a rotary as well as horizontal or onward motion
in the line of its axis. Opposite to the periphery or circumference of
this electrode I place another electrode and by preference I use one that
is in the form of a point or pencil the apex being in contact with the
circumference of the cylindrical electrode and near to one of its ends. If
motion be now given as herein-before stated to the cylindrical electrode
the opposite electrode will trace a spiral path over its surface
from one end to the other, the contiguity of the convolutions
being determined by the rate of its onward progression.
order to obtain the light I connect the opposite or pointed electrode
with the armature of an electro-magnet or with a coil of conducting
medium in such a manner that on the transmission of a current of
electricity this electrode is drawn or moved away to a suitable distance
from the other and then retains a fixed position until on breaking the
electric circuit it again renews the contact. I form the circuit of the
current so as to render the rotary cylinder an electrode of positive elec-
tricity, and the point or pencil an electrode of negative electricity. The
light-being by these arrangements produced on the circumference of the
cylindrical electrode, and its motion continuously bringing fresh surface to
the operation of the luminous portion of the current an uniform amount
of resistance is offered to its passage, and the light is generated with a
steady constancy due to that of the current itself. To obtain the maxi-
mum amount of light it is necessary to proportion the distance between
the electrodes to the intensity of the electricity employed. I provide
means for effecting this object by placing the electro-magnet or its
armature on a moveable support which will admit of the distance between
.them being increased or diminished at pleasure. The duration of the
light will of course depend upon the size of the rotary barrel electrode and
as by its motion which is derived from clockwork or other suitable means
it maintains a steady and permanent light I have in contradistinction to
other electric lights called this arrangement the electric constant light
apparatus.
In order that this part of my Invention should be fully ascertained
and in what manner it may be performed I will now proceed to describe]
and refer to the several Figures on the first Sheet of Drawings hereunto
annexed.

page_text: Figure 1 is a front elevation of one of my electric light apparatuses
complete. Figure 2 is a side elevation of the same, parts being removed
to shew the interior. Figure 3 is a plan of apparatus fixed on a base
board. In each of these Figures the same letters refer to like parts.
a is a hollow cylinder or barrel positive electrode of which a cross sec-
tion is shewn in Figure 13. 6 is the central rotary axis shewn separato
in Figure 7. c is a fixed hollow screw within which the central axis works
shewn detached in Figures 8 and 9 d d are clamp circular plates or discs
having an interior rim fitting the aperture in the barrel electrode, one of
the plates is fixed on the end of a hollow axis, the other end being formed
with a screw, by which to connect the second plate and thus clamp or hold
the electrode in position these are shewn separately in Figures 10 and 11.
Within this hollow axis the fixed hollow screw containing the central axis
is placed. One end of the central axis carries a pulley which is connected
by the chain or cord e with the driving pulley f actuated by clockwork
apparatus held by the frame g g hh are hollow standards supporting
the barrel electrode i is the negative electrode held by the pendant
socket j in which is a projection fitting in a recess or groove k in the
electrode to prevent its falling out. For the purpose of affording a con-
venient means of fixing the electrode, the socket is made to open in two
parts, one of which is removed in this Figure but they are shewn together
in Figures 5 and 6. Z is a part of the mouthpiece of the standard m; the
other part being fixed on the slide or door which is here removed. To
facilitate the passage of the current I line the inside of the mouthpiece
with platinum. The negative electrode passes freely through this mouth-
piece without lateral deviation when drawn upwards. n is a cord carried
over the pullies oo one end being hooked to a ring in the socket and the
other end to the bar p q is an electro-magnet fixed by the bracket r to the
plates which moves on another or bed plate t, secured on the block or
bridge of wood t'u is a screw working through the bracket r and employed
to adjust the distance apart of the magnet q and armature, w this arma-
ture is attached to a short arm x of the lever y which.is supported on the
axis 2. The long arm of the lever passes under the bed plate t, and ter-
minates in a forked end; To this fork a pair of spring nippers a¹ a¹ is
attached and these are so regulated by the screws 6' 6' working in the
bracket c' c' that at the moment the armature is attracted by the electro-
magnet they take hold of the bar p, fixed to the end of the chain, and
carry it down with the lever d' is a bent rod fixed to the armature which
as it is drawn to the magnet causes the rod to depress a short ivory stud
secured on the end of the axis e' carrying an arm furnished with a pin
at the end that drops in between the teeth of the wheel f¹ and thus stop

page_text: the motion of the clockwork when the current is cut off g' is an adjust-
ment acting on a balance wheel for the purpose of varying the rate of
motion is a spring regulated by a screw and serving to withdraw the
armature from the magnet on the occurrence of a break or loss of power
in the current kkkk' are screws to fasten down the base board ' to
the bottom of the case m'.
Still further to make plain the connection and general operation of the
several parts of the apparatus I shall now state the direction traversed
by the current. The screw P being brought into contact with a conductor
from the positive pole to the screw N with another conductor from the
negative pole of a voltaic battery or other suitable source of electricity,
the circuit will be from N to the standard h thence through the central
axis and screw clamp plate to the rotary barrel electrode. From this it
passes to the opposite point or pencil electrode and it is in so doing that
the great resistance to the passage of the current gives rise to heat and
light the amount of which is proportionate to the power of the current
and to the nature of the electrodes. From the pencil electrode the cir-
cuit is through the mouthpiece l and socket j down the standard m to a
wire by which it is carried around the electro-magnet to the screw P.
Of the remaining Figures in the first Sheet of Drawings Figure 4 repre-
sents a back elevation of the mechanism by which the negative electrode
is withdrawn n is a cord attached to the socket jp is a bar a¹ a' are spring
nippers fixed on the fork of lever y y b'b' adjusting screws working
through brackets fixed to the under side of case m. Figure 5 is a front
view of socket Figure 6 cross section of the same a the part which opens
or may be detached b aperture to contain electrode and n the chain or
cord. Figure 7 central axis which for the purpose of giving a rotary
motion to the electrode is made flat on one side for half of its length the
hole in the screw clamp plate being made of a similar form to receive it;
a, chain pulley. Figure 8 hollow screw to contain central axis, one end
terminates in a shoulder plate by which it is fixed in a recess formed in
its bearing standard. Figure 9 is an end view of this shoulder plate,
a being the aperture in which the central axis revolves. Figure 10 shews
the hollow clamp axis; an end view of the fixed clamp plate is shewn in
Figure 11.
a, clip or tongue which being held by the pressure of the
spring b, between the thread of the screw carries the electrode as it
revolves along the line of its axis. c loose clamp plate screwing on to
the end of the hollow axis when passed through the electrode. Figure 12
is a front view of a barrel screw electrode, the apex of the thread when
in motion in the apparatus being continuously brought under the point
of another electrode placed at right angles to it. Figure 13 is a cross

page_text: carbon.
The third part of my Invention relates to a mode of maintaining a
very uniform distance between a rotary disc positive electrode and a point
or pencil negative electrode, this mode consists principally in keeping in
contact with the periphery. of a rotary disc electrode a roller or pulley or
other contrivance which is connected by a chain or band or by levers with
a pendant or sliding point or pencil electrode, whereby as the positive
electrode diminishes, the negative electrode is permitted continuously
to advance without causing sudden fluctuations in the light.
The manner in which this part of my Invention may be carried into
effect will be understood by reference to the Figures in, the second Sheet
of the accompanying Drawings and to the following description.
Figure 1 is a front elevation of the complete apparatus and Figure 2
is a side elevation, part of the case and of one of the standards supporting
the disc electrode being removed to shew the mechanism. a positive disc
electrode to which a rotary motion is imparted by a pulley fixed on one
end of its axis being connected with another pulley driven by clockwork
held in the frame b-c negative electrode fixed in a socket sliding in the
standard & where it is held pendant by the cord e passing over pulleys
placed therein-f sliding. frame carrying a pulley around which the cord
is conveyed-g spring nippers attached to the lever h-i screws for regu-
lating the pressure of the nippers on the sliding frame-j axis of lever―k
armature borne on the end of the adjusting screw / which passes through
the short elbow of the lever-m is an electro-magnet supported on the
bed n, and held by the bracket o-p pulley over which the cord is con-
veyed and made fast to a cross pin at the lower end of the sliding frame
g- is a pulley fixed in this frame and held against the disc electrode
by the weight of the pendant socket and negative electrode-s s'are
hollow standards supporting the disc.
Upon connecting the binding screws P and N with a suitable voltaic
battery, the electricity will pass from N around the electro-magnet, and
up a standards to the disc electrode on the periphery of which the light
is produced. Through the negative electrode the electricity is carried to
the standards and thence to the second binding screw P-The action
of the apparatus is as follows-upon the soft iron or armature at one end
of the lever being attracted by the electro-magnet, the nippers attached
to the other end of the lever are drawn down carrying with them the pulley
frame through which the cord connected with the negative electrode is
passed the extent of this movement is restrained by an adjusting screw.
As the rotary positive disc is consumed the pulley in contact with its edge
will be raised thereby lowering in exact proportion the other electrode.

page_text: Upon the current ceasing to pass, the nippers liberate the frame, and the
negative electrode rests upon the disc ready for further use.
The fourth part of my Invention refers to improvements in producing
a succession of flashes or streams of light.
It has already been proposed to obtain electric light by a rapid suc-
cession of flashes resulting from the vibration produced by mechanical
agency of electrodes. I do not therefore intend to claim as new the
obtaining of electric light by a succession of flashes. I employ however
for the purpose one or more electro-magnets to give rise to or effect a
reciprocative or vibrative motion in electrodes and prefer to use the metal
mercury for the positive electrode in producing flashes or streams of light.
In Sheet 3 of the annexed Drawings, Figure 1 is a plan and Figure 2 a
side elevation partly in section of an arrangement by which this part of
my Invention may be carried out, as a lamp suitable for vessels at sea,
or locomotives on land, there being no liability to the light ceasing, and
as the flashes of light are produced with exceeding rapidity they appear
almost as one sparkling light-a, is a frame or case provided with suit-
able slides or doors for gaining access to the interior-b lens-c bent glass
vessel having a close fitting lid s, at the elbow-d, d, sockets or hollow
pistons working through the lid s, and connected by short rods with the
beams f, f, supported on the standards g g-hh, rods which unite the
short end of each beam with the balance i working on the axis j,-k, k,
are adjusting screws passing through the balance and holding the soft
iron armatures l, L. m, m' are electro-magnets-n is a reservoir or supply
vessel with an opening u at the top to admit the open end of the glass
vessel c, and also connected near the bottom with, the glass vessel by a
small tube or pipe p-t is a reflector-e, e, are two hollow pencil negative
electrodes securely fastened in their sockets-s is an aperture to admit
mercury into the reservoir-the various parts of the apparatus are
securely fixed to the base board q, which slides within the lamp and is held
down by the screws r, r. The path of the current is from the binding
screw N fixed in the iron reservoir containing the supply of mercury
which forms the positive electrode in the glass c, thence alternately
through each of the negative electrodes e, e² and around its electro-magnet
to the binding screw P. In this way the lamp continues in operation, as
the electro-magnets are excited they successively attract their armature
which drawing down the balance connected to the beams raises a negative
electrode from the mercury and produces a flash of light. At the same
time the short end of the other lever being raised by the balance causes
the other negative electrode in its turn to complete and then break the
circuit and thus give another flash of light. As mercury when used for

page_text: the positive electrode in the production of light undergoes a rapid evapo-
ration, I provide means, by carrying the bent glass vessel over into the
supply reservoir for its condensation therein, and to facilitate this I some-
times cover the mercury therein with water. I find it of great advantage
to employ hollow negative electrodes in connection with a positive elec-
trode of mercury.
1 sometimes employ steel armatures in connection with the electro-
magnet in place of soft iron, so that its residual magnetism shall serve to
retain the electrode or electrodes in the position assumed during the pas-
sage of the last current. On the arrival of each succeeding current, the
transmission of which is regulated by a suitable electrotome, the elec-
trodes are moved or drawn away one from another by the force originated
by the current, a flash or stream of light is produced, and the residual
magnetism holds the electrodes in position for another electric impulse.
Another mode whereby I produce successive flashes or streams of light
consists in the employment of a coil of conducting medium and by means
of an axial. bar or magnet used in connection therewith a vibratory
motion is given on the passage of the current to one or more elec-
trodes which may be arranged as herein last before described. In any
arrangement of a vibratory system of electrodes, I so direct the current
that it shall at every impulse impart a negative nature to the vibrating
electrode.
This part of my Invention is very suitable for lighting marine buoys
the electricity being conveyed through insulated submarine conducting
medium. Figure 3 in Sheet 3 of the Drawings represents the plan of an
arrangement by which I
propose to light up any number of marine buoys
or beacons one after another successively by the same electric current;
the buoys being moored around shoals or sand beds, as for instance the
Goodwin, would by the continuous running of the light completely sur-
round them with a belt of fire and thus afford a valuable means of prevent-
ing shipwreck-a is a submarine electric cable, communicating through
a flow and return insulated conductor with the light producing electrodes
placed under a strong bell glass or frame on each buoy. The two ends of
the submarine cable are placed in connection with an electrotome formed
as shewn in the Figure. One end of each insulated conductor is joined
to a binding screw numbered in the Figure similar to the buoy it is in
communication with, and this by means of a spring a' forms contact with
a projecting tooth of the barrel b, the axis of this barrel carries a toothed
wheel c, which is drawn round a distance of one tooth by a claw in the
end of the arm d, each time that the armature h, is released from the
electro-magnet-e is a lever borne on an upright axis f, and connected,

page_text: one end: with the upright g, working on an axis and carrying the arma-
ture,..the other. end is joined to the arm d,-i is a spring regulated by .a
screw and pressing back the armature when the current is broken-N.
binding screw from which the current passes around the electro-magnet
to the screw m, thence to the spring n in permanent contact with the
barrel. As each tooth of the barrel. during its rotary motion is brought
into contact with a spring the current passes to one pair of electrodes
which are ignited and drawn away. to a distance that will break the cur-
rent, the electro-magnet then ceasing to hold the armature its support
is forced back by the spring which causes the arm to draw on the toothed
wheel and bring the adjoining spring in contact with the next tooth upon
the barrel thus igniting the electrodes in advance and in this way the
light continuously.runs the round of the buoys.
The fifth part of my .Invention relates to the introduction of an induc-
tion coil (formed either with or without a condensing arrangement) to be
used in connection with a primary current, and one of my improvements
herein consists in giving any required motion to electrodes by the opera-
tion of the primary current, and producing light by means of the induced
current alone. I effect this operation by passing a primary current of
voltaic or other electricity through one or more induction coils and at the
same time move or regulate electrodes or their apparatus in any desired
way. To produce the light I connect the electrodes with the secondary
circuit of the coils, so that that current only shall pass through them and
cause ignition. I prefer not to cut off or suspend the primary current
but simply to change its direction by means of an electric reversing appa-
ratus.the construction of which is well understood. While therefore the
light is developed by the secondary current the primary current does not
cease to regulate the motion of the electrodes.
I perform the sixth part of my Invention by combining the currents
generated in an inductive coil with currents of magneto-electricity, pro-
duced by the motion of a conductor within the action of permanent
magnets, so as to increase its effect in producing light.
The seventh part of my Invention consists in the peculiar mode of
obtaining the electric light by which signals are effected. It comprises
the application and use of an electrotome or an arrangement of electro-
tomes, by which the current shall be let on both at rapid and at long
intervals, or at rapid at short and at long intervals. At each passage of
the current a distinct flash of light is produced, and this may be taken to
denote an unit, the short intervals the end of a number, and the long
intervals to signify either the termination of the signal, as when a repe-
tition of it is desired, or the end of a combination of numbers.
This

page_text: system may be made to represent words or sentences as well as numerals
and being easily understood is well adapted to lighthouses.
Figure 4 represents a side view of an electrotome suitable for signal-
ling the number three hundred and fifty-seven. It is placed on an axis
which forms part of the circuit of the current and as it revolves in the
direction of the arrows, by means of clockwork or other suitable power,
the successive projecting teeth are brought at intervals according to their
distance apart, in contact with a spring or moveable stud, thus closing
the circuit and producing light between the electrodes with which it is
in connection, as the distance to which the electrodes are separated
breaks the current the light is extinguished until by the motion of the
electrotome it is again renewed.
Lastly I propose to indicate to vessels by flashes of electric light, the
depth of water in harbours or on banks and to effect this by means of a
float within a tube, which by suitable mechanical contrivances as it rises
and falls, calls into operation different electrotomes, and these by com-
pleting the circuit of the current give rise to flashes of light in number
according to the depth of water in feet.
The manner in which I carry out this part of my Invention will be
understood on reference to the Drawings numbered 5 and 6 Sheet 3,
a is a hollow pillar or tube, on the top of which the cap b is screwed-
c, c are separate rows of insulated plates each plate being one foot long
and connected by an insulated conductor to a rotary electrotome which
corresponds by the number of flashes it is capable of calling forth, to the
height in feet that the float d, will be from the bottom of the water when
the brace spring f unites opposite plates. The electrotome is connected
with one pole of a battery and one of the rows of insulated plates with
the other pole. The pressure of the spring on the plates is regulated by
the nut g. It will be evident that the post should be fixed sufficiently
high above high-water mark to effect the required signals. Figure 6
represents a section of a revolving electrotome which would shew a
depth of eleven feet.
To distinguish this from other marine lights I make it a colored light,
by placing a colored glass before it, or by the use of my improved metal
electrodes described in the first part of this my Specification.
Having now described and particularly ascertained the nature of my
said Invention of improvements in obtaining light by electricity, and the
manner in which the same is or may be used or carried into effect, I
declare that I do not confine or restrict myself to the precise details or
arrangements which I have described or referred to, as many variations

page_text: may be made therefrom without deviating from the main features of my
Invention but I claim
First, the mode described of forming condensed gas-carbon electrodes
for obtaining electric light.
Second, the use of electrodes formed of compressed spongy or pow-
dered metals, or of a combination of metal powder and plumbago or other
form of carbon.
Third, the arrangement of electrodes and combination of mechanism
or means for the production of a constant electric light as herein-before
described in relation to the second part of this my said Invention, refer-
ence being had to the Figures on the annexed first Sheet of Drawings.
Fourth, the arrangements described of maintaining an uniform dis-
tance between a rotary disc electrode and a point or pencil electrode.
Fifth, the arrangements described relating to the fourth part of my
said Invention for producing a succession of flashes or streams of light,
as well as the use of two or more negative electrodes in combination with
a single positive electrode of mercury and the use of hollow negative elec-
trodes in combination with a positive electrode of mercury.
Sixth, the plan described herein, by which any number of marine buoys
or beacons may be successively illuminated.
Seventh, the arrangements or means for the production of electric
light by the use of a secondary or induced current as described.
Eighth, the combination of magneto-electric with secondary currents
for the production of light.
Ninth, the system or mode herein described in reference to the seventh
part of my said Invention for effecting signals by electric light.
And tenth, the arrangements described for indicating the depth of
water by electric light.
In witness whereof I the said Charles Weightman Harrison have
hereunto set my hand and seal this Twenty-eighth day of August,
One thousand eight hundred and fifty-seven.
CHAS. W. HARRISON. (L.S.).