IMPROVEMENTS IN THE CONSTRUCTION AND MANUFACTURE OF ELECTRIC INCANDESCENT LAMPS AND IN APPLIANCES FOR THE REGULATION OF ELECTRIC CURRENTS, THEREFOR AND FOR OTHER ELECTRICAL PURPOSES 23AL
Year: 1883

page_text: LETTERS PATENT to William John Lawrence Hamilton of Wandsworth in
the County of Surrey Electrician for an Invention of "IMPROVEMENTS IN
THE CONSTRUCTION AND MANUFACTURE OF ELECTRIC INCANDESCENT LAMPS
AND IN APPLIANCES FOR THE REGULATION OF ELECTRIC CURRENTS, THEREFOR
AND FOR OTHER ELECTRICAL PURPOSES
23
PROVISIONAL SPECIFICATION left by the said William John Lawrence
Hamilton at the Office of the Commissioners of Patents on the 7th June
1883.
WILLIAM JOHN LAWRENCE HAMILTON of Wandsworth in the County of Surrey
Electrician "IMPROVEMENTS IN THE CONSTRUCTION AND MANUFACTURE OF
ELECTRIC INCANDESCENT LAMPS, [AND] IN [APPLIANCES FOR] THE REGULATION OF
ELECTRIC CURRENTS [AND IN GOVERNORS] THEREFOR, AND FOR OTHER [ELECTRICAL]
PURPOSES
"
I make the filament or burner of bogwood such as that from fir, oak or yew, the
latter preferred as much superior but not often found. The material having been
cut up into thin sheets or the filament having been cut to the required length and
section is soaked in boiling water or other suitable liquid. The filament is then
bent into the required form while hot and pliable. It is then impregnated throughout
with tetrachloride of platinum (Pt Cl 4) and whilst wet exposed to the fumes of
chloride of ammonia (Am Cl) in a state of sublimation. The double salt
2 Am Cl + Pt Cl 4 is thus formed in the pores of the filament. The filament is
next treated with lime water, or with the solution of a salt (but not the chloride)
of calcium, barium strontium or magnesium until the pores are as nearly as
possible filled up with such salt. I may use a calcic oxalate dissolved in oxalic
acid for the preliminary softening and soaking instead of the boiling water. The
filament is then carbonized.
When the filament is to be applied for high tension current I treat the bent
filament with the aforesaid salt or salts at once and then carbonize it.

page_text: For mounting the filament I deposit copper or iron electrolytically on the ends
and give the copper or iron a slight coat of nickel or silver to preserve it from
oxydation.
The plug or piece on which the filament is to be mounted is made of a piece of
glass tube into which a looped doubled platinum wire is inserted leaving the loop
end projecting at one end and the two free wire ends projecting at the other end;
the tube is then heated and flattened so as to carefully seal the wires therein.
then flatten the loop or upper end of the wires cut the loop through longitudinally
and straighten the flat ends thus formed; the opposite or lower free wire ends are
then bent outwards into small hooks or loops and their ends sealed in.
For filaments to be used for greater candle power and for counteracting the
peculiar mutual frittering away action of the legs of the filaments I bend the free or
lower ends of the wires inwards and have them of such a length that they can not
be carried up through the inside of and slightly beyond the top of the tube before
being sealed, care being taken that these wires when sealed are well insulated from
each other by the intervening glass of the flattened tube. To the upper ends of
the inner wires I connect thin copper wires which are carried up looped and then
connected to the outer wires immediately below the flattened ends of same. These
latter are doubled or folded over lengthways and the filament ends having been
inserted in the nipped onto them. The inner looped copper wires thus placed
between the legs of the filament are not absolutely essential for the good working
of the lamp but tend to prolong the life of the-filament..
I form the globe from a glass tube the size of which I maintain at the lower end
of the globe while forming a fine tube at its upper end. The globe is best made
of an ovate spheroid form.
The lower tubular part of the globe having been flattened in accordance with
the form of the plug the latter is inserted and sealed tightly therein.
The socket or holder consists of a plug of ebonite or other suitable insulator
fitted with screw or other attachment for fitting to the electrolier. Two stout iron
or copper wires are passed through this plug insulated from each other and having
platinized hooks at one end of the plug to make contact with the aforesaid loop
ends of the lamp wires and having binding screws at their other end one on each
side of the plug. The plug may be oval in section and have an oval brass ring fixed
on the top from which ring two or more thin strips project which are formed with
slits and fit the lower part of the globe with a certain amount of spring action.
As regards the shape of the filament it may be in the form of a simple loop
and of an oval section. This section may be produced by pressing it between
rollers. For cutting the filaments I may use a roller mounted on a table and
formed with small grooves of the width and depth of the required filament and
separated from each other by steel knife edges. The bogwood having been cut in
sheets of a thickness rather more than that of the filament and of a width equal to
the length of the filament the grain running parallel to the width, the sheets are
immersed in boiling water and then placed on the table and the aforesaid roller
passed over them with considerable pressure thus cutting up the sheets into strips.
The table may be of metal faced with cardboard, sheet lead or veneer so as not to
injure the knife edges.
If the filament is to be cemented on to the wires instead of being clamped on
I use a cement of 20 parts of spongy copper and 3 parts of charcoal mixed with
tar. The spongy copper may be made by heating acetate of copper in a crucible
Jined with charcoal.
Before the globe is to be exhausted I charge it with hydrogen or nitrogen or
other gas which does not injure the carbon of the filament to displace the air. An
easily fitting solid glass rod may be inserted in the upper narrow tube of the globe
before exhausting to prevent injury to the tube while soft. In exhausting the
globe when the mercury in the pump falls with a smart tapping noise, that is when
the globe is perfectly exhausted, the filament is raised to incandescence the pumpp
being kept in action. This is to be continued so long as any gas is. evolved. The

page_text: filament is then heated to twice its candle power for a few seconds before finally
sealing the globe.
I generally place the aforesaid lamps in multiple are between a positive and a
negative conductor. These conductors respectively proceed from and return to a
dynamo machine which may be either shunt wound or not. In the latter case
if a certain number of lamps be turned off the others will glow too brightly so;
as to cause irregular flickering of the light and materially impair the durability
of the lamp filament if not destroy it altogether. In order therefore to prevent
these evils I use resistance in the main circuit or in that of the field magnets
in connection with an automatically adjusting solenoid. (or it might be electro-
magnet). The energy expended in overcoming the resistance is equal to that
which would be required to keep the number of lamps turned out, up to their
normal incandescence entailing a waste of electrical. and. mechanical horse power
and expense.
I therefore reduce the speed of the dynamo machine and thus
regulate the current or charge to each lamp by indirectly automatically and
proportionately reducing the speed of the engine or steam dynamo after the
resistance is inserted the resistance being automatically thrown out when the speed
of the dynamo has become sufficiently reduced. Instead of an ordinary resistance
I may use two fixed electro-magnets pulling against each other and connected
with a solenoid which completes the connection between the main circuit and the
resistance when required, I insert a solenoid in a shunt from the main lamp circuit
(or it might be an electro-magnet) the strength of which will vary with the
strength of current passing through it, and this solenoid surrounds the sleeve of the
ordinary or other centrifugal governor. The sleeve is made longer than usual and
made of brass or other non-magnetic material the lower portion being of soft iron.
The governor directly or indirectly actuates the throttle valve or expansion or
other slide valve. When the current in the main lamp circuit becomes two intense
there will be a proportionate increase of current in the shunt circuit, the resistance
will be connected, and the solenoid will thereupon draw in the sleeve and thus
reduce the speed of the engine.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William John Lawrence Hamilton in the Great Seal Patent
Office on the 7th December 1883.
WILLIAM JOHN LAWRENCE HAMILTON of Wandsworth in the County of Surrey,
Electrician "IMPROVEMENTS IN THE CONSTRUCTION AND MANUFACTURE OF ELECTRIC
INCANDESCENT LAMPS AND IN APPLIANCES FOR THE REGULATION OF
CURRENTS THEREFOR AND FOR OTHER ELECTRICAL PURPOSES
,,
ELECTRIC
I make the filament or burner of bogwood that is to say of wood found in peat
bogs in Ireland and elsewhere and such as that from fir oak or yew, the latter
preferred as much superior (but not often found) because it generally contains
over sixty per cent of pure carbon. I prefer bog yew to bog oak and I prefer bog
oak to bog-fir, but the latter is more easily worked
The filament
The material is cut up into thin sheets as for veneering the thickness of the
sheets being regulated by the section of the required filament. My next step in
the manufacture depends upon the kind of lamp I require. If I require a lamp
of low resistance the sheet is first soaked in boiling water or other suitable liquid
until it has become thoroughly pliable and is then placed in the machine for
cutting the filament which machine I describe later on. The sheets may be cut
of uniform thickness to be cut thinner in the middle than at the ends where it is
advantageous to have greater strength. The filament is then bent into the required
form while hot and pliable and then dried quickly. It is then impregnated
throughout with tetrachloride of platinum (Pt Cl.) by immersion in a solution
thereof and whilst wet exposed to the fumes of chloride of ammonia (Am Cl) in a
state of sublimation or immersed in a solution of chloride of ammonia. The double
salt 2 Am Cl + Pt Cl, is thus formed in the pores of the filament.
is next thoroughly dried at a gentle heat and then treated with lime water, or
with the solution of a salt (but not the chloride) of calcium, barium, strontium or
magnesium or a mixture of any or all of them until the pores are as nearly as
possible filled up with such salt. I may use saturated solutions but I prefer to
use solutions only half saturated and to repeat the operation as often as required
whereby the deposit is rendered more uniform. I find a solution of calcic oxalate
in HCl or NO, HO or other acid or suitable solution, or still better a solution of
calcic oxalate in hydrochloric acid, or a solution of calcic oxalate in nitric acid, or
a solution of calcic tartrate in tartaric acid, or calcic tartrate in a solution of
chloride of ammonia Where this last solution is used the special previously named
treatment with ammonic chloride in connection with the platinum treatment may
be omitted, as the free ammonic chloride in the calcium solution is sufficient for
the reaction. As other suitable solutions to be used at this stage of my process
I name strontic hydrate in water, baric hydrate in water calcic carbonate in water
impregnated with carbonic anhydride, and magnesic carbonate in solution of
carbonic anhydride in water.
I may use a calcic oxalate dissolved in oxalic acid for the preliminary softening
and soaking instead of the boiling water. The filament made from the sheet in
the manner described is then carbonized which may be done by embedding it in
finely pulverized charcoal graphite or other suitable carbon substance but strongly
heated and then cooled in an atmosphere of coal gas or other more or less dilute
hydrocarbon previously to packing the filament with it. This prevents oxygen
from being occluded in the pores of the carbon. After being protected or covered
in the usual manner the crucible or other vessel containing the filaments is placed
in the furnace, where it remains until the filaments are thoroughly carbonized.

page_text: When the filament is to be applied for high tension current I dispense with the
soaking of the sheets in boiling water and treat them with a boiling solution of a
salt of calcium, strontium, barium or magnesium or a mixture of any or all of
them. Whilst hot and wet I transfer the sheets to the cutting machine and after
cutting them up into filaments and bending into shape I immerse the filaments as
often as is necessary in the same solution and dry them and then carbonize them.
It will be observed that in treating the high resistance filaments I omit the
platinum process altogether.
For mounting the filament I either deposit copper iron platinum or other suitable
metal with a high fusing point electrolytically on the ends and if I use copper or
iron or other oxydisable metal I prefer to give it a chemical or electrolytical slight
coating of platinum nickel or silver to preserve it from oxydation and to preserve
good electrical contact with the flattened ends of the platinum wires to which the
ends are attached or I coat the ends with a conducting cement.
The plug or piece on which the filament is to be mounted is made of a piece of
glass tube such as b in Figure 1 of the accompanying drawings into which tube b
a looped double platinum wire A is inserted leaving the loop end projecting at one
end and the two free wire ends projecting at the other end. The tube is then
heated and flattened so as to carefully seal the wires therein. I then flatten the
loop or upper ends of the wires as shown at a¹ Figure 2 cut through the loop and
straighten the flat ends thus formed as shown at a Figure 3 the opposite or lower
free wire ends are then bent outwards into small hooks or loops and their ends
sealed in as also shown at Figure 3, Figure 2* is a plan section through the flattened
glass tube b.
For filaments to be used for greater candle power and for counteracting the
peculiar mutual frittering away action of the legs of the filaments, portions of the
carbon of one leg becoming detached and attracted to the other leg (the so-called
molecular bombardment), I bend the free or lower ends of the wires inwards and
have them of such a length that they can be carried up through the inside of and
slightly beyond the top of the tube b as shown at c c¹ Figure 4 before being sealed,
care being taken that these wires when sealed are well insulated from each other
by the intervening glass of the flattened tube. To the upper ends of the inner
wires c c I connect thin copper wires h and i as shown at Figure 5 which are
carried up looped and then connected to the outer wires immediately below the
flattened ends a² of same. These latter are doubled or folded over lengthways and
the ends of the filament k having been inserted in them, the flattened ends a² are
nipped on to them. The inner looped copper wires hi thus placed between the
legs of the filament are not absolutely essential for the good working of the lamp
but tend to prolong the life of the filament because I thus provide a wire inside of
cach filament leg and closer to it than the other leg; the potential of which wire is
very much nearer to the potential of, the filament leg to which it is nearest than
the potential of the other leg is. The platinum wire need 'not be so thick as
ordinarily because there are two paths for the current instead of one.
I form the globe from a glass tube the size of which I maintain at the lower
end of the globe while formning a fine tube of about 1/8th inch bore at its upper
end; Figure 6 shows such a form of globe. The globe is best made of an ovate
spheroid form as shown.
.
The lower tubular part of the globe having been flattened as shown at Figure 7
in accordance with the form of the plug 6 Figure 5 the latter with filament attached
is inserted and sealed tightly therein. The lower tubular part of the globe before
being flattened should be of such a diameter that the glass tube b Figure 1 before
being flattened can be passed into it easily. This part is then carefully fused to
ensure a perfect seal.
The socket or holder is shown at Figure 9. It consists of a plug A of ebonite
or other suitable insulator fitted with screw or other attachment A' for fitting to
the electrolier Two stout iron or copper wires B B¹ are passed through this plug
insulated from each other and having at one end of the plug hooks which may be

page_text: platinized and which serve to make contact with the aforesaid loop ends of the
lamp wires and having binding screws C C¹ at their other end one on each side of
the plug. The plug may be oval in section and have an oval brass ring fixed on
the top. Figure 10 shews the holder fitted with such a brass ring D from which
ring two or more thin strips in this case three strips E project which are formed
with slits and fit the lower part of the globe with a certain amount of spring
action.
.
As regards the shape of the filament it may for strength and simplicity be in the
form of a simple loop and of round or oval section. This section may be produced
by pressing it between rollers. For cutting the filaments I may use a roller
mounted on a table and formed with small circular concentric grooves of the width
and depth of the required filament and separated from each other by steel knife
edges. The roller is free to revolve in centres to which a handle is attached for
moving the roller properly guided over the table. Or the roller may be stationary
but free to revolve in centres while the table is moved under it the bog-wood having
been cut in sheets of a thickness rather more than that of the filament and of a
width equal to the length of the filament the grain running parallel to the width
the sheets are immersed in boiling water and then placed on the table and the
aforesaid roller passed over them with considerable pressure thus cutting the
sheet up into strips. The table may be of metal faced with cardboard, sheet lead
or veneer so as not to injure the knife edges. By varying the section and length
of the filament any desired resistance and candle power is obtained.
For
installations in parallel are I prefer 30 candles as a standard. A suitable width of
roller groove for such a power is 27 m. m. by a depth of 26 mm the wood sheets
being 28 m. m. thick and an effective length of 145 to 150 m. m. the ends being
say 3 m. m. thick. The electromotive force for such a lamp would be from 100
to 110 volts. Fifteen candle lamp filaments may be of the same section but only
half the length, which would enable two 15 candle lamps to be used in series, their
combined resistance being equal to one of 30 a matter of importance where the lamps
are arranged in parallel arc. If the lamps are arranged in series the section would
be much larger and the length less, they may be even as thick as 6 to 8 m. m., the
length being varied accoring to candle power required. The most serious objection
to the use of lamps in series viz: that if one filament fails or is put out the other
lamps go out, it has been attempted to be overcome by many patented automatic
devices and my automatic device to be presently described and used in connection
with one of the already patented switch devices does overcome all the difficulties,
so that for many purposes such as for street lighting the series system has
advantages but I prefer parallel arc for domestic use and where unskilled persons
have the management of the light. For a 20 candle lamp I may use a round
filament 2 m. m. in diameter by 130 m. m. long and taking the same electro motive
force as the 30 candle lamp. If the 30 candle lamp be made with a round filament
it may be 28 m. m. in diameter by 140-150 m m in length.
If the filament is to be cemented onto the wires instead of being clamped on I
use a cement of 20 parts of spongy copper and three parts of charcoal mixed with
tar. The spongy copper may be made by heating acetate of copper or other organic
salt of copper with about half its weight of charcoal and then heating in a crucible
after which it is again pulverized or I may heat the salt of copper in a crucible
lined with charcoal.
Before the globe, is to be exhausted I charge it with hydrogen or nitrogen or
other gas which does not injure the carbon of the filament to displace the air.
An easily fitting solid glass rod m Figure 7 may be inserted in the upper narrow
tube of the globe after first contracting the tube at the lower part 1 and
before exhausting. This rod m serves to resist the pressure of the atmosphere
and prevents injury to the tube while soft. The outer part of the tube is then
contracted or partly sealed as shown at Figure 7. I prefer to use a hydrocarbon
but as the fine tube Figure 7 is by this time drawn to a narrow neck it is
difficult to fill the globe through this neck with a hydrocarbon in a gaseous form.

page_text: I therefore proceed as follows I first warm the globe. well to rarefy the air within
it and while the globe is warm I introduce a few drops of benzoline or other
volatile hydrocarbon such as absolute alcohol turpentine or heavy carburretted
hydrogen into the small tube l. On cooling the globe the contraction of the air
forms a partial vacuum which sucks in the benzoline. I then attach to the
platinum loops forming the electrodes of the lamp two wires through which I can
send a current to the lamp while exhausting but this I do not claim separately
I then plunge the globe into a cold liquid having a high boiling point (such as
linseed or other oil) and whilst the exhaustion is proceeding I raise the temperature
of the liquid and of course that of the lamp globe and of the benzoline vapor
therein and maintain it at or near such boiling point until the exhaustion is nearly
or quite completed. I seal the tube if possible some distance from the lamp
before removing it from the boiling oil. Heating the globe first vaporizes the
benzoline and then rarefies its vapors in the lamp to a greater extent than the
exhaustion by means of a Sprengel pump can do. After the lamp has cooled
sufficiently the sealing can be completed as above described. In exhausting the
globe I first use an ordinary air pump to save time and then a mercury pump but
I do not claim this mode of exhausting. When the mercury in the pump falls
with a smart noise that is when the globe is perfectly exhausted the filament is
raised to incandescence the pump being kept in action.
This is to be continued so long as any gas is evolved. The filament is then
heated to about twice its candle power for a few seconds before finally sealing the
globe. Figure 8 shows the globe sealed and finished with a bead at the top.
Each lamp should be tested when made and labelled with the electro motive force
required to work it and assorted accordingly, a small margin of difference being
only allowed.
I generally place the aforesaid lamps in multiple arc between a positive and a
negative conductor. The conductors respectively proceed from and return to a
dynamo machine which may be either shunt wound or not.
•
In an installation in parallel arc it is especially necessary that all lamps should
take the same quantity of current and have an equal resistance although when
arranged in series the resistance may vary in each lamp if required provided that
the sectional area and conductivity of all the filaments length for length are the
same. If these differ the temperatures of the different filaments vary also and
thus some are overheated whilst others may not yield anything approaching to
their normal candle power. If a lamp is not heated sufficiently we do not get an
economical return in light for the power expended and on the other hand if the
filament of a lamp becomes overheated although we get a more economical
return of light for the power expended the life of the lamp is materially shortened
and we thus lose more than we gain. It is manifest that a lamp is therefore not
an independent and perfect contrivance in itself and that to perfect a lamp we
must combine it with some mechanism which will supply it with a never varying
current of the exact quantity and potential required to maintain it at its most
economical candle power.
Again suppose instead of one lamp in circuit we have a whole system the same
conditions will have to be fulfilled so long as the number of lamps in circuit
remains constant, but if the number of lamps varies, the supply of electricity
will also have to vary either in quantity, if the lamps are in parallel arc, or in
potential if the lamps are in series.
Although the general system on which I work remains the same throughout
it is obvious that to adapt it to all the different kinds of dynamos now in use, I
have to vary the details of construction. Again I have to vary the arrangement
according to whether the lamps are arranged in parallel are or in series.
"
In addition to the saving in wear and tear of lamps and keeping the light from
flickering and variation, my special governing arrangement saves fuel and where the
"dark room
system of regulation is in vogue, it saves the wages of three men daily
who are ordinarily required to attend to the valve of the engine. The simplest
J

page_text: form of governor is that which is used when the lamps are worked in series. In
this case it simply consists of an ordinary ball governor such for instance as the
one shown at Figure 11 the sleeve of which is made longer than usual. The upper
portion A of the sleeve for a few inches down is made of brass or other non-
magnetic substance and the lower part A which works in the solenoid B is of
soft iron, and may be rigidly attached to the upper portion. The solenoid B or
coil of insulated wire is placed around the sleeve A A¹ and at such a height that
when the governor is at rest a portion of the iron A' of the sleeve may project
below the bottom of the solenoid. The interior opening of the solenoid must be
of such a size that the sleeve of the governor may be free to revolve inside of it.
The solenoid B is supported by a bracket B¹. C is the driving pulley.
It is manifest that if a current of electricity passes through the coils of the
solenoid, the iron sleeve will have a tendency to lift and with it raise the balls of
the governor, and by the fork lever operated by the brass collars A' on the sleeve
tend to close the throttle valve more or less. Let us suppose that when the engine
is running at full speed the centrifugal force of the governor be sufficient to raise
the sleeve A A¹ one inch. Let us also suppose that the iron portion A' of the
sleeve projects three inches (in case of a large and powerful steam engine) below
the bottom of the solenoid coil B when the engine is at rest. It is evident that
when the engine is running at full speed the centrifugal force of the governor
alone will raise the sleeve one inch and leave two inches projecting below the coil.
Let us now while the engine is running at full speed pass a current of electricity
through the solenoid coil sufficient to raise the sleeve of the governor another inch.
There will now be one inch projecting below the solenoid coil. If at this height
the sleeve of the governor only just commences to act on the throttle or expansion
valve of the engine to which it is connected so that in its present position it is
full open but that upon the slightest upward motion of the governor sleeve it
commences to close, it will be manifest that so long as the current in the solenoid B
and the speed of the engine remains constant so long will the sleeve of the governor
remain at its present height. Let us now first suppose that the current remaining
constant the speed of the engine increases. The governor balls will revolve faster
the sleeve will lift and the speed of the engine be reduced to its former value.
Again let us suppose that the speed remaining constant, the current be augmented.
The speed will then be again reduced until equilibrium be restored.
Again, suppose both speed and current be augmented. We have here both
centrifugal force, and electro-magnetic attraction acting in the same direction and
so the speed is checked even more quickly than before
From these considerations it is plain that if the current passing through the
solenoid B be a portion of the current produced by a dynamo driven by the engine
governed by the above arrangement, the speed of the engine will be kept constant
and the supply of electricity from the dynamo will vary neither in potential nor
quantity so long as the resistance in the external circuit of the dynamo remains
constant.
Let us now suppose the external circuit of the dynamo to be composed of a
number of incandescent lamps arranged in series. It is clear that the total
resistance of the external circuit will be equal to the sum of the resistances of the
lamps composing the circuit plus the resistance of the mains. If now several lamps
be cut out, the circuit being bridged over by conductors of comparatively no
resistance, the speed of the engine remaining constant, the quantity of the current
will increase, whilst the electro motive force remains constant. But this is not
what we require. We want the quantity to remain constant (or nearly so) whilst
the electromotive force should vary. If however the governor solenoid B forms a
part of the circuit the current in it will increase at the same time as it increases in
the lamps. By this means the speed of the engine will be checked and equilibrium
restored, by the quantity being reduced to its former value. The connections of
the governing solenoid are as follows. One end of the wire forming the solenoid
coil should be attached to, or near to one of the brushes of the dynamo, say the

page_text: brush, and the other end of the wire to the electric main at a point between
that brush and the first lamp. This is better than sending the whole of the
current through the solenoid which would in most cases be.too strong. It also
admits of careful adjustment of the amount of current passing through the
solenoid by varying the resistance in the solenoid circuit. This is my governor
arranged in the simplest manner It is however a form that is not likely to be so
much used by me, since for most purposes I prefer the lamps arranged in multiple
arc (I may here state that the governor itself may be either horizontal or vertical;
the latter requires a more powerful current to operate it. I do not confine myself
to any centrifugal or other form or construction of governor as my solenoid
arrangement can be adapted to any form.)
In the multiple are arrangement we find that the governor acquires a more
complex form.
In this case instead of each additional lamp increasing the resistance of the
circuit as is the case in the series arrangement, we find that each lamp added
decreases the resistance by giving the current another path by which to pass
from the lead to the return. Hence if the governor solenoid were arranged as
for the series method, we should find it augment our difficulties instead of
removing them.
In this case therefore we must place the governing solenoid in a shunt circuit,
one end of its coil being connected with the positive brush, and the other with the
negative one. By this means with every increase in the resistance in the main
circuit we find a greater quantity of current flowing not only through each lamp
left on circuit, but also through the governing solenoid. This governing arrange-
ment however is not perfect in itself, although for small installations it might
perchance do sufficiently well. Its imperfection consists in this;-When some of
the lamps are turned out, the current in the remaining lamps is temporarily
increased, and at the same time, the current in the governing solenoid is also
increased. But when the speed of engine and dynamo are reduced to the amount
required to produce the exact current for maintaining the remaining lamps at their
normal candle power, it is found that the current circulating through the governing
solenoid is again reduced to its former proportions. In consequence the speed
of the engine would be again augmented, to be again, reduced and so on,
thus producing a constant variation in the speed, and a consequent flickering in
the light.
The simplest method of remedying this defect is by having a variable resistance
in the same circuit as the governing solenoid. If this resistance were greatest
when the dynamo were at full speed, and if the resistance were automatically
reduced in proportion to the reduction of speed of the dynamo, we should find
that as the speed of the dynamo was reduced by the action of the governor, so
would the amount of current flowing through the governing solenoid be increased,
and it would not be difficult to regulate this increase to the exact amount requisite
to maintain the governor sleeve in its right position. As an adjustable resistance I
may use any form of rheostat such as Trouvé's or I may use a special form such
as the one shown at Figure 12 consisting of two rods D of carbon firmly attached
to the sides of a rod G of insulating material such as ebonite. This insulating
rod G and carbons D may be made to slide freely in a glass (or other) tube H
closed at the bottom, and containing a sufficiency of mercury I or other fluid
conductor to rise to the top of the carbon rods when they are pressed down to the
bottom of the tube. If then these carbon rods D are of sufficient sectional area to
convey all the current they are required to convey without undue heating, and are
of at least half the resistance each of the whole distance required to produce the
necessary alterations in the current, it is plain that this if properly regulated will
be all that is required for perfecting the automatic governing arrangements. My
method for adjusting this rheostat is as follows:-
The bottom ends of the two carbon rods D are electrically connected by means
of a stout wire K, or a rod of carbon, whilst the upper ends of the rods are

page_text: I
II. The shunt dynamo.
III. The series dynamo.
There is also the magneto dynamo which however is not a common form, and
the different compound dynamos, which are more or less self regulating, but which
can generally be classed under one or more of the above heads.
Let us first consider the separately excited dynamo. This consists of a large
dynamo to supply the current for the lamps etc. whose field magnets are excited
by a smaller dynamo driven by a separate engine. Let us first suppose the lamps
aré arranged in series. The connections of the solenoid will be made as directed
above for lamps arranged in series, and the solenoid B will be placed around the
governor sleeve of the engine driving the larger dynamo.
The governor of the small engine driving the "excitor" may als have an
electrically controlled governor, the ends of the wire forming the solenoid of which
may be attached to the brushes of the exciter. By this means the electromotive
force can be adjusted whilst the quantity remains constant.
In this case
Let us again suppose that the lamps are arranged in multiple arc.
we require the electromotive force to remain constant, whilst the quantity varies
according to the number of lamps on circuit.
In this case I fit my automatic governor on the engine driving the exciter, and
I attach the ends of the wire forming the governor solenoid to the two brushes of
the separately excited dynamo. I thus cause the large dynamo to govern the
engine which drives the exciting dynamo.
The next class of dynamo under consideration is the shunt wound. If this
dynamo were used for lamps in series, the connections would be arranged as under
the head of lamps in series described. It is however not well suited for this
arrangement because the internal resistance is too small.

page_text: With the lamps in multiple arc I can connect the two ends of the wires forming
the shunt in which the governor solenoid is included to the two brushes as directed
above for lamps in multiple arc. I can also coil one or two layers of insulated
wire round the field magnets inside of the ordinary shunt winding and include
these layers of wire in the same circuit as the governor solenoid.
In this case the variable resistance of the self adjusting rheostat acts directly on
the field magnets as well as on the governor.
By this means the quantity of current in the field magnets is kept more
constant than by the other method, and this prevents the potential being so much
reduced by slackening the speed, so that the speed may be slackened more.
It is manifest that if the load of the engine is reduced it will run at the same
speed with less steam, and therefore this method of arranging the governor is
desirable where the potential is required to remain constant, whilst the quantity
varies.
In the series dynamo, if the lamps are also in series the connections of the
governor solenoid should be made as directed under that head. If in multiple arc
the connections of the shunt circuit including the governing solenoid should be
between the brushes of the dynamo, and another branch which may contain the
self adjusting rheostat may proceed from the main cable after it leaves the field
magnet coils. By this means we may shunt an automatically varying portion of
the current past the field magnets and so vary the intensity of their field.
This self-adjusting rheostat should be inserted in the same circuit as the
governing solenoid in all cases except where the lamps & are arranged in series
where it is omitted. This completes the governor in so far as its automatic
governing and regulating properties are concerned, but it is not yet perfect, as it
does not protect lamps from injury by sudden variations in the strength of the
current, as for example the sudden extinguishing of a large number of lamps, or
the fracture of a portion of the lead. This might force a too great charge of
current through the remaining lamps on circuit, and so injure them or even break
them down during the short period in which the governor was reducing the speed
to the required amount. To obviate this defect I adopt the following expedient.
Between one of the brushes and the first lamp I make a break in the main
conductor of such width that the current cannot bridge it over by an arc. This
appliance is illustrated by Figure 13.
This break may be say half an inch wide. Let each of the ends of the cable I
where it is divided be connected with a solid block Cu of copper, and let these
blocks of copper be held apart from each other by a layer K. of insulating
substances Let each of the upper surfaces of these blocks of copper be level so
that a third block C of copper by being laid on the top may bridge over the gap
and enable the full current to pass without any appreciable resistance.
If necessary
to ensure good electrical contact the faces of these blocks may be platinised, or
iridium plated.
To the loose copper block C which bridges over the other two and which I term
the bridge I attach a metal rod L which works in guide H to ensure the block
fitting accurately against the other two, and to the other end of the rod L
I attach a cylindrical piece B of soft iron which forms the core of a solenoid A.
When the bridge C is in contact with the copper blocks the core B projects say
one fourth of its length outside the solenoid A so that any current passing through
the solenoid would tend to draw the bridge C away from the copper blocks Cu
and so break the connection, between the two detached portions of the cable the
solenoid A Figure 13 which is connected with the bridge in the same circuit as
the governing solenoid B Figure 11. To prevent the normal current which passes
through the solenoid A from breaking the contact of the bridge C with the copper
blocks. I arrange a helical spring inside the hollow of the solenoid so as to
press on the end of its core and keep it in its place. This spring can be adjusted
to any desired pressure by a regulating screw G and so the amount of current
which will lift the bridge from the blocks can be adjusted at will. Care must

page_text: however be taken in all cases so to adjust. the spring that the greatest normal
current which passes through the shunt circuit is insufficient to lift the bridge.
E. M. are magnets in a bridge circuit from the main I and through which the
current passes when the bridge block C is disconnected.
Figure 14 is a diagram illustrating this mode of regulating a multiple are
system when the dynamo is shunt wound 1 is the commutator of the dynamo 2. 2..
the brushes 3 the shunt circuit of the field magnet coils, B is the governor solenoid*
Figure 11. F is the solenoid which works the rheostat H Figure 12, and which is
in a shunt circuit 4. 4 from the main circuit M, M. Its resistance bears a certain
ratio to the portion of M, M, marked O between the points P, P, at which the
shunt joins the main. A is the bridge solenoid (Figure 13) E. M. are the magnets
Figure 13, 5, 5 is a shunt between the two main conductors and including the
governor solenoid the rheostat and the bridge N, N, are lamps or other receivers.
If now any excessive current passes through the lamps N and in consequence
through the governing circuit 5 the bridge C. Figure 13 is at once lifted, and the
current completely stopped. This however would temporarily extinguish all the
lights which could not be permitted, and would very imperfectly fulfil my object.
I therefore as already stated provide another path for the current to find its way
to the lamps, and one which will at all times consume in some way all the excess
current whatever its amount may be. I therefore provide the two powerful electro
magnets E M. Figure 13 of horseshoe form, and place them with opposite polės
facing each other, and only separated from one another by discs of india rubber or
other elastic substance, or they may be rigidly attached to a frame, with the poles
close together, but not touching. These magnets may be wound in one or two
ways. Either each magnet may be wound with a cable which can with safety
carry the whole current generated by the dynamo, and the two magnets be
joined in series as shown in Figure 13 with the ends of the cable attached, one to
each of the copper blocks Cu in connection with the bridge C, or the magnets may
each be wound with a cable capable of carrying with safety only half of the
current generated and then connected together in multiple are that is to say the
two ends of E and M together and the two ends likewise. Let us suppose
the resistance of the magnets to be 2.5 ohms and the resistance of the bridge C
when in contact to be 001 Ohm the current through the magnets would be trifling
but if the bridge were removed the full current would flow through them and a
certain part of the current depending on its strength would be converted into
energy and so consumed by the effort of the magnets E M to attract each other
thus the excess of current passing would be reduced to a minimum and the lamps
in a great measure protected.
I will now proceed to give a more detailed description of the different portions
of the apparatus and the various modifications which may be effected in them.
The reheostat may be varied in form to a considerable extent. It may consist
as already described of a cylindrical rod of ebonite with two carbon rods half
embedded in it one on each side with their bottom ends joined by a carbon or
metal bar.
Another plan would be to have a U tube such as shown at Figure 15 with the
carbon rods D in one leg H and fixed in position and a piston G to work in the
other leg H moved by the core of the solenoid as in Figure 12. The bent tube
is partly filled with mercury so that as the piston G descends in one leg H¹ the
mercury may arise in the other leg H containing the carbons D and so vary the
resistance as required.
The rheostat might also as stated be of a Trouve construction.
In all cases the resistance of the rheostat whether consisting of carbon rods
German silver spiral, or platinum, silver alloy spiral, should be determined by the
special requirements of the engine and dynamo it is intended to adapt it to.
Also care will have to be taken that the sectional area of the carbon rods or metal
spiral be such that undue heating is avoided.
The solenoid coil working the rheostat, and the rheostat itself together with all

page_text: the apparatus connecting the two might be fitted in a case for compactness, as in
Figure 12 the solenoid being at the top with the glass tube containing the rheostat
below the moving parts i.e. the solenoid core L and rheostat (or piston) working
in guides M between the two. This contrivance could be fixed in any convenient
place It is evident that in this rheostat the mercury in the tube will vary its
height in proportion to the amount of electricity generated by the dynamo and so
by fixing a scale behind the glass tube containing it specially graded for each
instrument a rough ammeter may be made of it, or if preferred it may be graded
to show the number of lamps in actual use at the time.
The bridge also allows of considerable modification in its construction The
break in the conductor may as already described consist of two fixed blocks of
copper C with a third movable block C superimposed upon them.
It may also
consist of two blocks to each of which one end of the cable is attached, the one
being fixed and the other one which is arranged to lie on the top of this one,
making good electrical contact therewith to be movable and attached to the core. of
the solenoid which regulates its movement
In describing that portion of the governor which acts directly on the expansion
or other valve of the engine I have hitherto only taken one form of the arrange-
ment i.e. that form of it which is used in connection with a ball governor.
however easily seen that the same system could be applied in many ways.
It is
Before however noticing another form of governor I must describe a modification
of the form at present in use which has its advantage. That is to make the
iron portion A¹ Figure 13 of the sleeve loose so that in case of any accident
happening to the electrical portion of the governor by which the current might be
prevented from circulating through the governing circuit, the ordinary centrifugal
governor might be relieved of the weight of the iron sleeve and so be enabled to
act on the engine and save it from racing itself to pieces.
This would not of course prevent the engine running at a much higher speed
than before but since to obtain anything like regularity of working it is always
necessary to run an engine driving a dynamo well within its speed, this excess
would not be sufficient to race the engine to pieces.
Another arrangement of the governing solenoid where it is not desired to use a
ball or centrifugal governor would be to attach to the valve spindle a solid cylinder
of soft iron, and make this the core of the solenoid, so arranged that the attractive
power of the solenoid should tend to close the valve, and be counterbalanced by the
force of a weight or of a spiral or other spring, which spring could have its
strength regulated and adjusted by hand, by means of a screw or other suitable
arrangement. Instead also of having the solenoid act directly on the valve
spindle, the solenoid might act on the valve by means of a lever or lever and cam
or any other suitable contrivance. All these solenoids in the circuits with the
governing solenoid itself included must be wound with wire of sufficient sectional
area to carry with perfect safety and at such a temperature as not to impair their
insulation, the largest current they will have to take. The resistance required
must be made up by the wires connecting the parts or by resistance coils.
Galvanised iron wire may be used if preferred to copper &c for making up the
required resistance.
And having now described the nature of my said invention and in what
manner the same is to be performed I declare that I claim.
First-The application of bogwood to the construction of incandescent filament
burners as set forth.
Second-The impregnation of filament burners with spongy platinum for the
purpose of lowering the electrical resistance of same also the mode of applying the
platinum substantially as set forth.
Third: The treatment of filament burners with a salt of calcium, barium,
strontium or magnesium or a mixture of same substantially as and for the purpose
set forth,
Fourth-The use with filament burners of intermediate wire loops for the

page_text: purpose of counteracting the Crookes's effect substantially as described and shown
in the drawings.
Fifth The mode of regulating and governing the speed of dynamo driving
engines and specially the governor solenoid in combination with the "bridge" and
electro magnet and where required also with the variable resistance or rheostat for
adjusting the power of the governor solenoid substantially as described and shown
in the drawings.
In witness whereof I the said William John Lawrence Hamilton have hereunto
set my hand and seal this first day of December in the year of our Lord One
thousand eight hundred and eighty three.
WILLIAM JOHN LAWRENCE HAMILTON (L.S.)