IMPROVE- MENT IN THE METHOD OF AND MEANS FOR DEVELOPING ELECTRIC CURRENTS AND LIGHTING BY ELECTRICITY
Year: 1878

page_text: LETTERS PATENT to Thomas Alva Edison, of Menlo Park, in the State of
New Jersey, United States of America, for the Invention of "IMPROVE-
MENT IN THE METHOD OF AND MEANS FOR DEVELOPING ELECTRIC CURRENTS
AND LIGHTING BY ELECTRICITY.”
Sealed the 14th January 1879, and ḍated the 23rd October 1878.
PROVISIONAL SPECIFICATION left by the said Thomas Alva Edison at the
Office of the Commissioners of Patents on the 23rd October 1878.
THOMAS ALVA EDISON, of Menlo Park, in the State of New Jersey, United
States of America. "IMPROVEMENT IN THE METHOD OF AND MEANS
DEVELOPING ELECTRIC CURRENTS AND LIGHTING BY ELECTRICITY."
FOR
I make use of an electric generator in the form of a very large tuning fork, the
same may be magnetized or not, and the same is firmly supported in the middle,
and the free ends are vibrated by mechanical force, such as small steam cylinders,
with a piston rod connected to each end of this fork, or any other device, such as a
crank, may be used to keep the free ends in vibration; but little power is required
to keep up the rate and amplitude of vibration that would result if the free ends
were drawn aside and then allowed to vibrate like a tuning fork. The mechanical
force applied to keep this large fork in vibration is converted into electricity by
placing upon the fork several magnets, and opposite to them stationary electro-
magnets, the helices of which are so connected by commutators that the induced
current set up
in the helices by the approach and recession of the cores will be con-
veyed to a line upon the principles known in connection with magneto-electric
machines.
The electric energy thus set up is carried by a wire to the lighting apparatus next
described; or it may be used cat a distant station for vibrating by magnetism a
similar large tuning fork, from which mechanical movement can be given by the

page_text: action of a pawl on a wheel or a crank moved by the mechanical vibrations of the
tuning fork.
The electric light is derived by the passage of the current through a spiral coil
of wire, or through a leaf or strip of metal, or through carbon or any other material
that will become incandescent. The incandescence of bodies under electric action
has been known, this portion of my improvement relates-to-the-manner-of-regu
lating the current, so that it can never become so intense as to melt or injure the
light-producing body. To effect this I make use of an automatic apparatus that
becomes operative according to the intensity of the current to check, divert, or
partially neutralize the action of the current in the light-giving body.
The heat developed. is caused to expand a wire or other body either by the
passage of electricity through it or by its proximity to the source of light, and this
expansion gives a mechanical movement through a lever or similar device to operate
a circuit closing device, to shunt-or-short-circuit-more-or-less-of-the.current, or to
throw a resistance into the circuit, and thereby lessen the electric current passing
through the light-giving body and prevent injury to the same. The same result
is attained by the expansion of confined air acting on a diaphragm, or by directing
And
a current of air upon the light-giving body to lessen the temperature thereof.
in some instances I employ a secondary battery in a local circuit, that is opened or
closed mechanically to throw the electric energy into the coils of platina or other
light-giving bodies; a number of these coils or light-giving bodies are placed in
one circuit, and means employed for preventing the breaking of the circuit by any
injury to one of the lights.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Alva Edison in the Great Seal Patent Office on the 23rd
April 1879.
THOMAS ALVA EDISON, of Menlo Park, in the State of New Jersey, United
States of America. "IMPROVEMENT IN THE METHOD OF AND MEANS FOR
DEVELOPING ELECTRIC CURRENTS AND LIGHTING BY ELECTRICITY."
The first feature of this Invention relates to a means for developing a current of
electricity by mechanism, so as to obtain the necessary electrical force cheaply; and
the second part of this Invention relates to the clectric light itself, the method of
regulating the intensity of the light and preventing injury to the same, and the
peculiar devices that are employed in au incandescent state to give the light.
It has long been known that if two electro-magnets, or an electro-magnet and
à permanent magnet, be drawn apart or caused to pass by each other, that electric
currents will be set up in the helix of the electro-magnet.
It has also been known that vibrating bodies, such as a tuning fork or a reed,
can be kept in vibration by the exercise of but little power. I avail of these two
known forces, and combine them in such a manner as to obtain a powerful electric
current by the expenditure of a small mechanical force.
In Fig. 1 of the Drawing a tuning fork a² is represented as firmly attached to a
stand 62; this fork is preferably of two prongs, but only one might be employed.
upon the principle of a musical reed. This vibrating bar or fork may be two
metres long, more or less, and heavy in proportion; it has its regular rate of
vibration like a tuning fork, and the mechanism that keeps it in vibration is to
move in harmony; a crank and revolving shaft, or other suitable mechanism, may
be employed, but I prefer a small air, gas, or water engine applied to each end of
the fork.
The cylinder a' contains a piston and a rod 6' that is connected to the end of the
bar, and steam, gas, water, or other fluid under pressure acts within the cylinder,
being admitted first to one side of the piston and then the other by a suitable
valve; the valve and direct-acting rod c² are shown for this purpose.
The bar or fork a³ may be a permanent magnet or an electro-magnet, or else it
is provided with permanent or electro magnets. I have shown an electro-magnet c¹
upon each prong of the fork, there may be two or more on each, and opposed to
these are the cores of the electro-magnets d, hence as the fork is vibrated a current
is set up in the helix of each electro-magnet d in one direction as the cores approach
each other, and in the other direction as they recede.
This alternate current is available for electric lights, but if it is desired to con-
vert the current into one of continuity in the same direction a commutator is
employed, operated by the vibrations of the fork to change the circuit connections
each vibration, and thereby make the pulsations continuous on the line of one
polarity.
Q
A portion of the current thus generated may pass through the helices of the
electro-magnets c¹ to intensify the same to the maximum power, and the remainder
of the current is employed for any desired electrical operations wherever available.
I however use the same especially with my electric lights, but I remark that
electricity for such lights may be developed by any suitable apparatus.
I have represented commutator springs or levers c³, c¹, operated by rods that
slide through the levers c³, c, and by friction move them. When the prongs a², a²,
are moving from each other the contact of levers c, c', will be with the screws
40, 41, and the current will be from line 1 through c¹ to c, thence to c³, to 41, 43,
and to circuit of electro-magnets d, d, and from d, d, by 42 to 40, c, and line as
indicated by the arrows. When the prongs a, a, are vibrating towards each other
the circuit will be through c³, c, c³, 42, in the reverse direction through the circuit
and magnets d, d, back to 43 and by c* to line.

page_text: Platinum and other materials that can only be fused at a very high temperature
have been employed in electric lights, but there is risk of such light-giving sub-
stance melting under the electric energy. This portion of my Invention relates to
the regulation of the electric current, so as to prevent the same becoming so intense
as to injure the incandescent material. The current regulation is primarily effected
-by-the-heat-itself,-and-is-automatic.
In Fig. 2 I have shown the light-producing body as a spiral a connected to the
posts b, c, and within the glass cylinder g. This cylinder has a cap and stands
upon a base m, and for convenience a column n and stand o of any suitable
character may be employed. Most of the other Figures are in the form of diagrams-
to more clearly represent the electrical connections. I remark that it is preferable
to have the light within a case or globe, and that various materials may be employed,
such as alum water, between two concentric cylinders to lessen radiation, retain the
heat, and lessen_the_electric_energy required, or colored or opalescent glass, or
solutions that reduce the refrangibility of the light, such as sulphate of quinine,
may be employed to modulate the light; and the light may either be in the atmos-
phere or in a vacuum.
The materials that I have found especially adapted to use as light-giving sub-
stances are set forth hereafter.
The electric circuit, Fig. 2, passes by line 1 to the post r and by a wire to the
lever f, thence by the wire or rod %, cap l, wire e, to the post c, through the double
spiral a to the post b, and by a metallic connection or wire to the post n and line 4,
and so on through the electric circuit and the light be developed in a.
The rod k will expand in proportion to the heat of the coil or in proportion to the
heat developed by the passage of the current through the fine wire k, and if the
heat becomes dangerously high injury to the apparatus is prevented by the expansion
of rod moving the lever f to close the circuit at i and short circuit or shunt a
portion of the current from the coil a and reducing its temperature; this operation
is automatic and forms the principal feature of my Invention, because it effectually
preserves the apparatus from injury.
The current need not pass through the wire or rod k as the expansion thereof by
the radiated heat from the coil a will operate the lever f, as indicated in Fig. 3, but
the movement is not so prompt.
If the light-giving body is a globule or small bar of silicon, boron, titanium, or
other substance, between carbon, platinum, or other metal rods, as shown in Fig. 4,
the spring will be employed to press the leverf and hold the parts in position.
The expansion of the parts a, k, by the heat from the current short circuits the current
as before.
In Fig. 5 the lever f is represented as within a glass, so that a vacuum can be
employed. The rod k may be of carbon, titanium, oxide, or any other conducting
body.
In Fig. 6 the expansion rod is represented as adjacent to the light-giving body
and acted upon by radiated heat as well as by the heat from the passage of the
current.
In Fig. 7 is represented a light-giving body formed of a platina or similar wire
around which carbon is made to adhere by pressure; the same becomes luminous by
the action of the electric current.
In Fig. 8 the spiral a is similar to that in Fig. 2, but a springt is used as a safety
to maintain the electric circuit unbroken if the wire or coil a should fuse and
thereby break the circuit; the current passes by wire 1, contact point 2, and block
, to line 4 when switch is in contact with 2; this throws the light out of action;
but when is moved to 3 the current goes by 1, f, k, a, to i and line 4; but if a or k
is broken the spring lever f closes to and current goes by 1, f, t, to 3, and by switch
to and line 4.
In Fig. 9 the switch when swung into contact with 2 presses the spring t upon
lever fand short circuits the current from k and a through the rheostat R that
is of equal resistance to the light-giving material. When the switch x is.moved

page_text: gar is brought into action, and the lever regulates the current as before
described.
In Fig. 10 the switch x when at 3 allows the current to pass through the
resistance coil R or rheostat that is of equal resistance to the light-giving material,
so that other lights are not influenced by lighting or extinguishing one electric light;
the other parts are like Fig. 2.
Fig. 11 represents an electric light like that shown in Fig. 6, only a spring and arm
take the place of the lever.
Fig 12 corresponds to Fig. 7 except that the spring árin f is used instead of the
lever.
Fig. 13 represents a carbon pencil or rod and spring lever; the carbon itself in
this case expands when the current is too strong and the spring short circuits the
current and becomes as before an automatic thermal regulator.
In Fig. 14 the light-giving body a is represented as a strip of platina or similar
foil, and there is a safety switch t in the form of a spring, and this is used in' addition
to the spring or lever f, so that in case of the spring being, interfered with at by
dust or oxyd upon the contact points the rod by a slight additional expansion
touches the safety spring t and short circuits the current.
Fig. 15 represents two strips of platina a, a If the strip a expands under heat
so as to cause lever to leave spring lever f' and break the circuit, that cannot
happen until the spring f¹ rests upon the contact point ; this allows the electric
circuit to divide and pass through both a and at; this reduces the temperature of
both and the two are maintained in the circuit until the contraction of a separates
f¹ and i.
In Fig. 16 the lever spring f¹ when it comes in contact witli i closes the
shunt circuit through the rheostat R, that lessens the power of the current' on the
platina strip a. The springs is adjustable to maintain the proper tension on the
lever f.
In Fig. 17 the end of the spring lever f rests upon a small platina wheel 10
that is upon an arbor in jaws at the end of the screw 11. When this screw is
turned one way it causes the wheel to touch the spring and extinguishes the light
by short circuiting it. When the screw is turned the other way the contact is
broken and the light induced. By the movement of the jaw and roller up and
down the platina wheel is revolved progressively by two stationary spring
pawls 12 and 13 acting on a ratchet wheel on the arbor of the wheel 10. By
this device a new contact surface is brought into action each time the light is
turned on.
In Fig. 18 three bent levers f are shown, the vertical ends being in a cup of
mercury to which one line wire is connected. The circuit passes through these
levers fand foil a, but when the foil becomes too hot it expands and allows the
levers to make contact with and short circuit the current; one of the three levers
will be almost sure to operate, but if not and the light-giving body a still expands
the point 15 will touch the spring 16 and throw the circuit through the resistance
R. In place of the levers last described three or more springs may be used, as in
Fig. 19, the action being the same as levers; or four or more springs may be used as
in Fig. 20, there being an adjustable spring 18 to apply a slight tension to the strip
of platina and to preserve the continuity of the circuit should the springs fail to
connect. The automatic thermal circuit regulation is in some instances effected by
the heat given by the electric light to air or gas in a confined vessel. The apparatus,
Fig. 21, corresponds generally to that shown in Fig. 2, except there is a diaphragmi
of thin metal or other material across below the perforated base that holds the
glass g, so that this diaphragm will be pressed downward by the expansion of the
air contained in the glass, and when the maximum temperature is obtained the
current will be short circuited by the point on the diaphragm making contact with
the insulated 'spring 21. The current passes by the wire 1, metallic head 7, incan
lescent strip, netallic base m and column, to the line 4. When the heat of the
spiral reaches within a few degrees of the melting point of said spiral the air in the

page_text: glass g has become expanded and the diaphragm is bulged outwardly and makes
contact within the spring 21 and the current is short circuited; the current now
being through wire 1, spring 21, diaphragm v, metallic base m and coluinn, to the
line 4. If the circuit should fail to close by the contact of the diaphragm and spring
21-the-further movement of the diaphragm will bring the spring 21 in contact with
-the screw i, and the short circuit will be through the spring 21, screw i, and metallic-
column to the line 4. It is to be understood that in all cases the action of the short
circuit or shunt is momentarily to lessen the current through the light-giving sub-
stance, and the circuit-closing-devices-play-up_and_down at the contact point
maintaining uniformity of brilliancy in the light.
The device shown in Fig. 22-acts the-same-as before-indicated, but the coil is
horizontal and the wires reach it by passing through a piece of chalk or similar
---material.resting upon a base m and the short circuiting is by contact with the screw
i of a platina projection on the diaphragm. A spring circuit closer may-be-used-as-
shown in dotted lines. If mercury or a liquid is introduced in the confined space,
containing also the light, and the air or gas heated thereby, a tube may lead to a
circuit-closing cup, as shown in Fig. 23, to short circuit the current when the
maximum temperature is obtained.
A
In lighting by electricity it is often important to use a secondary battery in
connection with the main current. The diagram, Fig. 24, shows four electric light
coils a, a, a, a, in a secondary circuit containing cells S, B, with plates in a conducting
liquid, and the lever 28 is vibrated by an electro-magnet 29 or by clockwork; when
the lever 28 is in contact with 39, the current from line 1 passes through 29 and
S, B, to 4, but when 28 leaves 39 the line is closed, but a local circuit is made
between 28 and 30 through the coils a and secondary battery, the discharge of this
secondary battery gives the light, and the movement is so rapid that the light
appears continuous. A single secondary battery may be introduced with one or
more lights, as in Fig. 25, the expansion of the light-giving material short circuiting
the current through the secondary battery S, B, the light-giving device may be a
spiral such as that shown in Fig. 2, the same being illustrated by dotted lines.
coil a³ may be used in a vessel containing water or other fluid, as seen in Fig. 26,
said coil being of less resistance than the light, so as to heat the water and operate
the circuit-closing diaphragm. Instead of a rheostat in the shunt circuit I some-
times employ a button of carbon 32, as seen in Fig. 27. In this case the spring
lever bearing upon the carbon button lessens the resistance by the increase of
pressure as the platina strip expands, and as it contracts and lessens the pressure on
the carbon button the resistance of that carbon button increases and a greater
portion of the current is sent through the platinum: strip; this regulation is very
accurate. If a helix of wire 33 is placed in the same position as the carbon as seen
in Fig. 28, the action will be the same, for when the coils of the helix touch cach
other the resistance will be less in the shunt than when the helix is distended by
the contraction of the platina strip or wire a, and the proportion of current passing
through a may be increased by the contraction of a, and the reverse.
struction prevents electric sparks, as the metallic circuit is continuous.
electro-magnet is introduced in the electric circuit, and its armature spring is set
up strongly, so that it will not respond until the maximum current is flowing
through the circuit, then the movement of the armature can be made to short
circuit the light-giving body, as illustrated in the diagram, Fig. 29, and thereby
lessen the current at the light, or it may be made to throw in a resistance or
One lever for
rlicostat R to lessen the flow of the current, as shown in Fig. 30.
spring circuit closer may be made to regulate the flow of electricity through several
lights. The diagrain, Fig. 31, illustrates several lights placed in one or more
derived circuits, each light being regulated independently by its own thermal
regulator. Fig. 32 represents ranges of lights, one branch circuit being connected
at the upper ends of the lights, and the other circuit wires to the lower ends to the
circuit-regulating levers. Fig. 33 illustrates the circuit connections of ranges of
lights, in which the top of one light is connected with the bottom of therext, the
This con-
When an

page_text: circuit-regulating springs falways acting in the circuit.
machine or other source of electricity is represented at a².
.
The magneto-electric
A variety of helices, coils, ribbons, and other forms of light-giving materials are
illustrated in Fig. 34 to 42, and in Figs. 48, 49, and 50, and I remark that in all
cases the light is due to the incandescence of the body, and that the thermal
regulator of the circuit is to be adjusted or made to act automatically to lessen the
electric current before the same becomes sufficiently intense to injure the light-
giving substance; this point will vary according to. the material employed in the
light. A cylinder of platina foil around a rod of lime gives an excellent light, and
strips, wires, rods, beads, and pieces of iridium, ruthinum, rhodium, osmium, titanium,
and other metals that fuse at a high temperature may be used; also conducting
oxides may be used, such as oxides of titanium. In Fig. 43 the two strips of
platina a, a', are connected at their. ends to the large and small pulleys 50 and 51,
and the lower end of a is connected to the spring f, and of a to the block 52. If
the foil a expands, it allows the pulleys to be rotated by the spring f, drawing off
foil from 50, and thereby increasing the length of the foil that is incandescent, and
increasing the resistance in the circuit. The same effect is produced by the device
shown in Fig. 44, in which the axial electro-magnet a has a suspended core; as
the electric current increases the core is drawn into the helix and the pulleys 50
and 51 turned so as to lengthen the strip of foil a. Fig. 45 shows a cylinder
of platina foil a as the light-giving material. Fig. 46 shows a magnet a' in the
wire between 1 and i. When the spring f touches i the current passes through the
magnet, and its armature closes a metallic circuit that divides the electric current so
that it does not all pass through the foil. In Fig. 47 the lever f, as it descends,
comes into successive contact with the yielding points 56, and the current passes
more freely from 1 to 4 in proportion as the one or more of the resistance coils may
be short-circuited by the lever f.
When the electric force is generated by a magneto-electric machine, it is important
to regulate the speed of the machine in proportion to the strength of the current,
so as to prevent injury to the machine when the electric lights are extinguished. I
effect this either by an index or galvanometer at the central station to denote to the
engineer the strength of the current, so that he can regulate the machine, or else a
governor is employed to throw in resistance or to short circuit the electric
current.
Fig. 51 is a modification of the device shown in Fig. 21. There is a chamber g²
connected by a tube to the glass g, and this chamber g² is covered by a diaphragm
g³, over which is a lever f. When the spiral a reaches its maximum heat, the
expanded air acts upon the diaphragm g³ and moves the same, so that it is brought.
in contact with the lever f; this in its turn makes contact with the screw 2, and the
current is short-circuited.
Fig. 52 shows another arrangement of parts, whereby the heated air in the.
glass operates the lever that short circuits the current when the burner reaches
its maximum heat. The glass y rests upon the top of the case or box h, and within
this box there are flexible chambers 5, h6, similar to those used in an aneroid
barometer; there is an opening in the top of the box, through which a tube from
the chamber h³ passes, so that the air may have free passage from the glass globe or
shade g to said chambers. Upon the under part of the lower chamber there is a
lever connected thereto at f* and pivoted at 5, and a contact point fo on said
lever is contiguous to the lever f' that is pivoted to the adjustable block f³.
The current enters by the line 1 and passes by the screw 23, spring 22, and wire
to the lever f, thence by contact fo, and wire to the metallic support f10 and
burner a, and by the other metallic support f¹ to the wire 30 and line 4. When
the maximum heat is attained by the burner, the heated air as it expands acts
within the flexible chambers ho, ho, and bulges them downwardly, moving the
lever f, and bringing the point fe in contact with the lever f, and breaking the.
circuit between f' and f to the burner a. The current now passes by line 1,

page_text: screw 23, spring 22, wire 24, lever f7, contact f6, lever f, resistance coil R, and
wire 30, to line 4.
The resistance R is equal to that of the burner a, and said resistance prevents
excessive sparks at the contact points. The block f8, upon which the lever f" and
point fare attached, is movable, and is adjustable by the screw f12. By moving
the block towards the burner, the circuit is broken-to-the-lamp-and-closed-
through fand f, and in so doing the circuit from 1 is broken between the
spring 23 and screw point 22. The reverse movement causes the lamp to be
-automatically_connected.
The burner shown in Fig. 52 is composed of six. spirals connected as shown in
Fig-55,-so-that-the-electric current-passes through all of them.
•
In Fig. 54 the same arrangement of circuits is shown as in Fig. 52, but the heated
air acts upon mercury in a tube to expand the mercury, move a float, and operate
the levers and f, and thereby break-the-circuit-to-the-lamp,-and-close-it-to-the-
rheostat R.
In the sectional elevation, Fig. 56, and sectional plan, Fig. 57, the thermal regu-
lator is similar to that shown in Fig. 20, but the burner or lamp is upon a swinging
arm or bracket, so that it can be swung like a gas fixture. The bracket as is sus-
tained by a socket and pin at 68. 1 is one of the electric conductors; the same is
insulated and passes into an opening in tlie bracket, and thence to the electric light,
and the return circuit is through the pipe as to the wire 4, or to the gas pipe if the
bracket is upon a gas pipe. The circuit-closing levers fare within and pivoted to
a metallic case a that is provided with a door for allowing access to the parts.
The levers are sustained at their moving ends by a yoke a¹0, see Fig. 58, connected
to the light-giving body a, and said moving ends are contiguous to a platina bar i
on a block adjustable by the screw ul. The current enters by the wire 1, and
passes to the plate a¹, wire as, head L, light-giving body a, levers f, case a, bracket
as, to the line 4. If the heat of the burner a becomes too high, the light-giving
body expands and allows the levers f to drop and make contact with i, and thus
offer a short route for the current, the same passing by the wire 1, plate al2, wire a¹,
block i, levers f, case a, bracket as, and line 4.
Fig. 53 is a diagram, illustrating a method of measuring the amount of electricity
used. c is à box into which the wires c, c10, from the main conductors enter.
3
Rio
is a coil of very large wire, whose resistance is proportioned to the number of
burners used in the house. This resistance is but the fractional part of the resist-
ance of a single lamp. An electrolytic cell c is used as the meter; this cell, which
contains a solution of copper, has two electrodes of copper, one of which is very
thick, while the other is very thin.
The small portion of the current which passes through the cell carries over copper
and deposits it upon the thin plate. If one lamp is placed in connection, it draws
current from the main, and a proportionate quantity passing through the cell effects
a deposit upon the thin plate; if another lamp is connected, double the quantity is
deposited, and so on. At the end of any period, say one month, the plate is taken
by the inspector to the central office and accurately weighed. As the deposit of
copper upon the thin plate will be proportioned to the total amount of current
passing into the house, the same becomes a correct measure or standard for the
charge for the electricity supplied.
When the deposited plate is taken out another one is to be substituted.
In said Fig. 53 I have shown a single lamp a, having, say, 1000 ohms resistance
placed in one branch, and in another branch I have shown four electric candles or
burners a, a, a³, a', in one lamp, the burners being in close proximity and arranged
in two branch circuits, the resistance of each branch being 2,000 ohms; the two
branches will jointly offer a resistance of 1,000 ohms the same as the resistance of
one lamp a. By this arrangement various numbers of lamps may be placed in
branch circuits between the same main conductors and the resistance be equal in
each branch...

page_text: In Fig. 59 the thermal regulation is effected by the electro-magnets e, c². The
current from one line passes through the spiral a, and then through the electro-,
magnets e, e, lever es, contact screw e, lever e¹o, and screw e¹¹ to the other line
wire 4. The levers are provided with retractile springs, and their tension is
adjusted so that the magnets will not attract the levers if the current is of such
intensity as to produce the proper incandescence of the light-giving body; if the
intensity of the current should exceed this proper point, then the magnets attract
their levers and keep them vibrating, thus breaking the circuit at the points e³
and el, and weakening the current passing through the burner a.
Two magnets are used in order that the spark at the contact points may be
lessened.
Fig. 60 shows the same form of thermal regulator as that shown in Fig. 59, but
only one magnet is employed.
In Fig. 61 the lever es of the electro-magnet e acts upon a lever e¹ that has a
spring to draw it towards e¹. When the current is of the proper intensity the
circuit passes through the spiral a, magnet es, lever et, and contact e to the line 4; if
the current becomes too inteuse the lever of ef is attracted and the lever e¹² is moved
from breaking the circuit to the burner; this is but momentary, for the
spring e draws the lever e upwards, and this latter moves the lever e¹², again
closing the circuit to the burner, and if the current continues to be too intense, the
lever is kept vibrating, opening and closing the circuit and weakening the current
to such an extent as to prevent all danger of the fusion of the light-giving body. In
Fig. 62 the lever e acts upon a lever e¹² and opens the circuit more quickly than by
the direct action of the lever e
In Fig. 63 the circuits are so arranged that the magnet e is in a branch circuit
and the current divides, part going to the magnet and the principal part to the
light. If the current becomes too intense the magnet attracts the lever e and
breaks the current at e³.
Fig. 64 shows a magnet provided with two coils, the current passing through in
opposite directions. The coil 2 is of large wire and is in the main circuit with the
burner, while the coil is of great resistance and shunts the burner and coil 2º.
The inequality of the resistance of the burner produced by rise of temperature
serves to disturb the balance, the magnet becomes energized and attracts the
lever and opens the circuit.
Fig. 65 shows a thermal regulator consisting of a bent tube containing mercury,
which latter is expanded or contracted by the heat of the current passing through
the same.
A float in the mercury at the open end of the tube is connected to the
lever and there is a second lever f' provided with a contact point or screw that
presses upon f¹ so long as the electric current is of the proper intensity. As the
mercury expands and by the float raises the lever f, the lever frises also and
presses the continuity of circuit until f' touches the stationary contact i; then if
the mercury continues to expand f separates from fand the circuit to the burner a
is broken.
The device shown in Fig. 66 operates the same as that in Fig. 60, but the clectro-
magnet is adjustable nearer to or further from its armature lever in order that said
lever may vibrate quickly or slowly according to the distance of the armature lever
and magnet from each other. In Fig. 67 the lever e is kept away from the
magnet e by a flat spring e" instead of a retractile spring; said spring e¹ is upon
a block moved by the screw e¹ so that the spring can bear with more or less
pressure upon the armature lever and thus determine the point at which the lever
will be attracted by the magnet and consequently regulating the amount of current
passing to the burner a.
In Fig. 68 a thermal regulating coil is shown within the flexible aneroid
chambers ho, ho, the heat from the coil acts upon the air within said chambers and
operates the levers f, f¹, the same as has been described with reference to Fig. 52.
I claim as my Invention,-
First. The combination with an electric light of a thermal circuit regulator to

page_text: to divert the current or a portion thereof from the light, substantially as set
-forth.
Third. The combination with the electric light and a resistance of a circuit closer
operated by heat, and serving to place more or less resistance in the circuit of the
electric light, substantially as set forth.
Fourth. The combination with an electric light of a diaphragm operated by the
expansion of a gas or fluid in proportion to the temperature of the light to regulate
the electric current, substantially as set forth.
Fifth. The combination with a vibrating body, similar to a tuning fork, of
-mechanism-for-maintaining-the-vibration,-and-magnets,-cores,-and-helices, whereby
a secondary current is set up so as to convert mechanical motion into electric force
or the reverse, substantially as set forth.
Sixth. The combination with electric lights, substantially such as described, of
means for regulating the electric current to the saine in proportion to the heat
evolved in the light so as to prevent injury to the apparatus, substantially as set
forth.
In witness whereof, I, the said Thomas Alva Edison, have hereunto set my
hand and seal, this Second day of April, A.D. 1879.
Witnesses,
THOMAS ALVA EDISON.
(L.S.)
STOCKTON L. GRIFFIN, of Menlo Park, N. J.
GEORGE E. CARMAN,
"
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