Improvements in Electric Arc Lamps for use in Search-light Projectors and other purposes.
Year: 1890

page_text: Date of Application, 19th Feb., 1890
Complete Specification Left, 19th Dec., 1890-Accepted, 24th Jan.,
1891
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps for use in Search-light
Projectors and other purposes.
1, The Honourable CHARLES ALGERNON PARSONS of the firm of C. A. Parsons & Co.
Heiton Works, Newcastle-on-Tyne, in the County of Durham, Engineer, do
hereby declare the nature of this invention to be as follows:-
In electric are lamps hitherto used for search light projectors, in which the carbons
have been controlled by a solenoid, a difficulty arises from the fact that the solenoid
has always been used in a vertical position and any variation in the angle of the
projector while using the search light destroys the adjustment between the pull of the
solenoid and the carbon regulated by it. The light is thus rendered unsteady.
The main object of my present invention is to overcome this difficulty and obtain
equilibrium between the pull of the solenoid and the pull of the carbon at all usual
angles of inclination of the projector.
In order to accomplish this I incline the line of movement of the carbon and the
solenoid core, at angles to the vertical which may be about 10° to 15° but other
moderate angles will suffice. I so arrange matters that the angle of the line of
movement of the solenoid core is at a greater angle to the vertical line than the line
of movement of the carbon. The difference between the angles may vary
within moderate limits, but I prefer to make the angle between the lines of
movement of the carbon and the solenoid core the same as the angle between the line
of movement of the carbon and the vertical.
The solenoid core is connected to the carriage actuating the carbon in such manner
that the weight of the carbon and sliding carriage is just balanced by the weight of the
its core. If the
solenoid core and the magnetic pull or suck of the solenoid upon
carbons approach each other too closely, the increase of current at once increases
the intensity of the suck and the carbons are pulled apart to such a distance that the
arc is maintained and the forces balance. The elements causing this balance are, the
weight of the carbon and carriage, on the one hand, and the weight of the solenoid
core and the magnetic puil on the other. As the magnetic pull is constant for any
given position of the core, and amount of electric current without reference to the
angle of inclination, it follows that if the solenoid and carbon be vertical and their
lines of movement be parallel to one another, or if their lines of movement be
parallel without being vertical, any deviation from a vertical position will disturb
the balance. The intensity of the pull of the carbon and carriage upon the cord
connecting to the solenoid core will diminish in proportion as the angle increases;
the intensity of the pull of the core upon the cord will also diminish so far as it is
caused by the weight of the core but as this weight is necessarily considerably less
than the weight of the carbon and carriage there is a less absolute loss of the effect of
the weight and consequently the balance is distributed in such manner as to cause the
solenoid to pull the upper carbon away from the lower and bring about irregular
action.
When the lines of movement of the carbon and the solenoid are inclined to each
other so that the solenoid core is at a greater angle to the vertical than the carbon,
then inclining the projector causes the pull due to weight of the core to diminish more
rapidly than the pull due to the weight of the carbon and carriage and in this way the
absolute variation in the pull of both is approximately equalized for all moderate
angles of movement. The return of the projector to its first position causes the reverse
action to take place.
By my device of arranging the lines of movement of carbon and solenoid core in
lines not parallel to each other I secure a nearly uniform action upon the carbon and

page_text: a steady are notwithstanding elevations or depressions of the projector through
moderate angles.
My invention may be carried into effect by different modes of construction but I
prefer the following simple arrangement :-
I mount a steel bar of oblong section in au inclined position upon a portion of the
projector frame and sink feathers or keys in the edges of this bar. Upon this 1 slip
a carriage having four easy running grooved wheels which run upon the feathers.
The carriage carries the upper carbon and runs very easily upon the steel bar. To
the upper part of the bar is attached a pulley and a suitable cord passes over it con-
necting at one end with the carriage and at the other end passing under a pulley
attached to the upper end of the solenoid core then fixing to a projection from a
solenoid attachment above the core.
The solenoid is placed upon the same portion of the projector frame as the steel
bar, but with its axis at a greater angle to the vertical line.
When the core is sucked in it acts upon the cord and raises the upper carbon.
When the weight of the carbon and carriage overcomes the solenoid pull then the
upper carbon falls. In this simple manner I provide for the maintenance of a steady
light not withstanding moderate change in the angle of the projector. The lower
carbon may be held in any convenient manner but I prefer to support it in a holder
furnished with a ball and socket joint and having an internal or external screw
arrangement which permits of the vertical adjustment of the carbon so that the
position of the arc may be controlled laterally by the ball and socket joint permitting
freedom of movement and vertically by the adjusting screw. The necessity for
separate co-ordinate lateral adjustments is thus entirely dispensed with.
This invention thus relates principally
(1) To the arrangement of solenoid in which the angle of solenoid and angle of
the line of movement of the upper carbon is different so that for moderate inclinations
the balance of forces necessary to control the arc is not materially affected.
(2) To the arrangement of upper carbon holder to allow free movement by
using grooved pulleys. The connections may also be made by levers instead of
cord and pulleys between the solenoid and the carbon carriage. I may also use a
parallel motion linkage to hold and constrain the upper carbon if I so desire it without
departing from the essential features of my invention.
(3) To the arrangement of bottom carbon supported by holder carried in ball and
socket joint and the adjusting screw described.
Many modifications in detail may be made but the description I have given shows
the manner in which I prefer to carry my invention into effect.
Dated this 18th day of February 1840.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for Applicant.
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps for use in Search-light
Projectors and other purposes.
I, The Honourable CHARLES ALGERNON PARSONS, of the firm of C. A. Parsons
and Co., Heaton Works, Newcastle-on-Tyne, in the County of Durham, Engineer,
do hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and. ascertained in and by the following
statement:
In electric arc lamps hitherto used for search light projectors in which the carbons
have been controlled by a solenoid, a difficulty arises from the fact that the solenoid
has always been used in a vertical position and any variations in the angle of the
projector while using the search light destroys the adjustment between the pull of
the solenoid and the carbon regulated by it. The light is thus rendered unsteady.
The main object of my present invention is to overcome this difficulty and obtain

page_text: equilibrium between the pull of the solenoid and the pull of the carbons at all usual
angles of inclination of the projector. In order to accomplish this I incline the line
of movement of the carbon and the solenoid core at angles to the vertical which may
be about 10° to 15° but other moderate angles will suffice. I so arrange matters that
the angle of the line of movement of the solenoid core is at a greater angle to the
vertical line than the line of movement of the carbon. The difference between the
angles may vary within moderate limits but I prefer to make the angle between
the lines of movement of the carbon and the solenoid core the same as the angle
between the line of movement of the carbon and the vertical.
The solenoid core is connected to the carriage actuating the carbon in such manner
that the weight of the carbon and sliding carriage is just balanced by the weight of
the solenoid core and the magnetic pull or suck of the solenoid upon its core. If the
carbons approach each other too closely the increase of current at once increases the
intensity of the suck and the carbons are pulled apart to such a distance that the are
is maintained and the forces balance. The elements causing this balance are the weight
of the carbon and carriage on the one hand, and the weight of the solenoid core and
the magnetic pull on the other. As the magnetic pull is constant for any given
position of the core, and amount of electric current without reference to the angle of
inclination, it follows that if the solenoid and carbon be vertical and their lines of
movement be parallel to one another, or if their lines of movement be parallel without
being vertical, any deviation from a vertical position will disturb the balance. The
intensity of the pull of the carbon and carriage upon the cord connecting to the
solenoid core will diminish in proportion as the angle increases; the intensity of
the pull of the core upon the cord will also diminish so far as it is caused by the
weight of the core but as this weight is necessarily considerably less than the weight
of the carbon and carriage there is a less absolute loss of the effect of the weight and
consequently the balance is distributed in such manner as to cause the solenoid to pull
the upper carbon away from the lower and bring about irregular action.
When the lines of movement of the carbon and the solenoid are inclined to each
other so that the solenoid core is at a greater angle to the vertical than the carbon,
then inclining the projector causes the pull due to weight of the core to fiminish
more rapidly than the pull due to the weight of the carbon and carriage, and in this
way the absolute variation in the pull of both is approximately equalizei for all
moderate angles of movement. The return of the projector to its first position causes
the reverse action to take place.
By my device of arranging the lines of movement of carbon and solenoid core in
lines not parallel to each other I secure a nearly uniform action upon the carbon and
a steady are notwithstanding elevations or depressions of the projector through
moderate angles.
My invention may be carried into effect by different modes of construction but I
prefer the following simple arrangement:-I mount a steel bar of oblong section in
an inclined position upon a portion of the projector or frame and sink feathers or
keys in the edges of this bar. Upon this I slip a carriage having four easy running
grooved wheels which run upon the feathers. The carriage carries the upper carbon
and runs very easily upon the steel bar. To the upper part of the bar is attached a
pulley and a suitable cord passes over it connecting at one end with the carriage and
at the other end passing under a pulley attached to the upper end of the solenoid
core then fixing to a projection from a solenoid attachment above the core. The
solenoid is placed upon the same portion of the projector frame as the steel bar, but
with its axis at a greater angle to the vertical line.
When the core is sucked in it acts upon the cord and raises the upper carbon.
When the weight of the carbon and carriage overcomes the solenoid pull then the
upper carbon falls. In this simple manner I provide for the maintenance of a steady
light notwithstanding moderate change in the angle of the projector. The lower
carbon may be held in any convenient manner but I prefer to support it in a holder
furnished with a ball and socket joint and having an internal or external screw
arrangement which permits of the vertical adjustment of the carbon so that the

page_text: position of the are may be controlled laterally by the ball and socket joint permitting
freedom of movement and vertically by the adjusting screw. The necessity for
separate co-ordinate lateral adjustments is thus entirely dispensed with.
This invention thus relates principally
(1) To the arrangement of solenoid in which the angle of solenoid and angle of
the line of movement of the upper carbon is different so that for moderate
inclinations the balance of forces necessary to control the arc is not materially
affected.
(2) To the arrangement of upper carbon holder to allow free movement by using
grooved pulleys. The connections may also be made by levers instead of cord and
pulleys between the solenoid and the carbon carriage. I may also use a parallel
motion linkage to hold and constrain the upper carbon if I so desire it without
departing from the essential features of my invention.
(3) To the arrangement of bottom carbon supported by holder carried in bail and
socket joint and the adjusting screw described.
Many modifications in detail may be made but the description I have given shows
the manner in which I prefer to carry my invention into effect.
Referring to the accompanying drawing which is a side elevation partly in section
of an electric are lamp for use in a search light projector constructed in accordance
with my invention, the steel bar A has formed upon it or sunk in it the feathers a a
and the carriage B moves freely on the bar by means of the four grooved wheels b.
The carriage B carries the upper carbon C while the lower carbon D is attached to
the lower part of the bar by a bracket d, a ball and socket joint and a holder d².
The holder d his a screw d³ which allows of vertical adjustment, and the ball and
socket joint together with the cranking of the holder d permits of ready lateral
adjustment. By these arrangements the are may be brought into correct focus.
The solenoid E is also attached to the bar A and its core E' acts upon the movable
carriage B by the corde which passes over the pulleys e and e¹ and is attached to
the carriage and the frame of the pulley e'.
The slide is so arranged that it moves in a line parallel to the line the line of
movement of the upper carbon and this line of movement is set at an angle such as k
to the vertical line fg. The angle may be about 10° to 15°. If a vertical line m
be drawn, and the line of motion of the core E¹ which is n be caused to intersect
it, then the angle o must be greater than the angle k, and I prefer that the angle o
shall be double the angle k. That is, the angle of the line of movement of the core
with the vertical is preferably double or nearly so the angle of the line of movement
of the carbon with the vertical line.
By this disposition as herein before explained the equilibrium between the pull
and weight of the solenoid and the weight of the upper carbon and carriage B is not
disturbed by moderate change in the angle of the projector while in use for search
purposes. The arc is maintained in this lamp in the manner well known in arc lamps
by the action of the solenoid E and core E so that closer approach of the carbons
causes increased current through the solenoid and consequent increased suck on the
core. This causes the core to pull the carbons apart until the forces balance. The
excess of weight of the carriage and carbon over the core E¹ causes the approach if
the current diminishes. It is evident that if the angles of the line in which the
carriage B and the core E¹ move, be parallel to each other, then if the lamp be moved
angularly, the effective weights acting on the pulley e by the cord e¹ will diminish in
each case proportionally to the weights.
If both weights were equal then the balance would not be disturbed; but as in
order to secure the action of the lamp the carriage and carbon together are necessarily
heavier than the core E', it follows that the effect of the weight of B and C will
diminish more rapidly than that of E' and so without any increase in the intensity of
the current the upper carbon will be raised. By arranging the angles as described
and illustrated the effective weights of E diminishes or increases more rapidly by
inclination or return to the vertical than that of the carriage and carbon and so the
equilibrium is maintained so far as the difference between the balancing weights are

page_text: concerned. The only cause which will produce separation or approach of the carbons
is a change in the current due to the consumption of the carbon or in the circuit
supplying the lamp.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is-
(1) In an arc lamp which requires to be nioved angularly or moved to varying
degrees of inclination, securing a constant or nearly constant difference of weight pull
between the carriage and solenoid by the arrangement of carbon carriage so that its
line of movement and the line of movement of the solenoid core are inclined from
the vertical line and the angle of the solenoid core is greater than the angle of the
line of carriage travel substantially as and for the purposes herein before described and
illustrated in the accompanying drawing.
(2) The arrangement of upper carbon carriage and holder travelling on a feather
or key by grooved pulleys to secure free movement as illustrated.
(3) The arrangement of bottom carbon holder with adjusting screw and ball and
socket joint substantially as described and illustrated.
(4) The arc lamp for use in projectors substantially as hereinbefore described and
illustrated in the accompanying drawing.
Dated this 18th day of December 1890.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for Applicant.