IMPROVEMENTS IN ELECTRIC ARC LAMPS
Year: 1882

page_text: LETTERS PATENT to William Hopkin Akester, of Glasgow, in the County of
Lanark, North Britain, Electrician and Engineer for an invention of
IMPROVEMENTS IN ELECTRIC ARC LAMPS
.
PROVISIONAL SPECIFICATION left by the said William Hopkin Akester
at the Office of the Commissioners of Patents on the 23rd May 1882.
WILLIAM HOPKIN AKESTER, of Glasgow, in the County of Lanark, North
Britain, Electrician and Engineer, "IMPROVEMENTS IN ELECTRIC ARC LAMPS
"
This Invention has for its object, by improved automatic mechanism, to increase
steadiness and uniformity of action in electric are lamps.
In a lamp made with the improvements the carbons are vertical and the holder
of the upper carbon is fixed to a spindle formed with one or more screw threads of
quick pitch and which works in an internally screwed block fitted so that it can
turn in a short tube or guide. The internally screwed block has formed on it a
ring which is by preference of a conical form and is made with fine teeth; and on
opposite sides of the toothed ring there are teeth fixed to a forked lever centered
on a fixed part of the frame. The lever is connected to the core of a solenoid
through the coil of which the lamp current passes, and when the lever is held up
by the solenoid its teeth engage with the ring of the internally screwed block and
prevent that block from turning; but when from the consumption of the carbons
or other cause the strength of the lamp current is lessened the solenoid allows the
lever to fall and set free the internally screwed block. This block then rotates
which allows the screwed spindle to descend and the carbons approach each other.
On the full strength of current being reestablished the solenoid raises the lever,
wich engages with the internally screwed block and preventing its rotation lifts it
and the screwed spindle and carbon the distance desired for the luminous arc.
The solenoid may be provided with a second or shunt coil of high resistance as
usual to render its action certain; or an electro magnet may be used instead of the
solenoid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Hopkin Akester in the Great Seal Patent Office on the
22nd November 1882.
WILLIAM HOPKIN AKESTER, of Glasgow, in the County of Lanark, North
Britain, Electrician and Engineer "IMPROVEMENTS IN ELECTRIC ARC LAMPS
"
My said Invention has for its object by improved automatic mechanism to
increase steadiness and uniformity of action in electric arc lamps.
In a lamp made with my improvements the carbons are vertical, and the holder
of the upper carbon is fixed to a spindle formed with one or more screw threads
of quick pitch, and which, without itself turning, works in an internally screwed
block or short tube fitted so that it can turn freely in a short tube or guide. The
internally screwed block is arranged to be acted on by the core of a solenoid which
core when itself raised by the action of the solenoid lifts the block or screw tube
by parts preventing it from turning, but these parts becoming disengaged when
the screw tube is lowered so that the screw tube can then turn and allow the
spindle to descend which it does by its own weight. The contrivance thus, in an
extremely simple manner, provides at once for "striking the arc" (or separating
the points of the carbons to, the extent required for forming the arc) and also for
the progressive movement or feeding downwards of the upper carbon as the
carbons become gradually consumed. The electric current passing through the
solenoid coils may be either the main current actuating the lamp or a shunt
current; or the solenoid may be compound or made with two coils, a main and a
shunt coil acting oppositely to each other, or in any other equivalent or suitable
manner, or an electromagnet may be used. When the carbon points are in contact
and the current is passing the solenoid core rises to its highest position which is
determined by an adjustable stop, and in doing so lifts the screw tube together
with the spindle and the upper carbon and strikes the arc. As the carbons
consume the are current weakens and the solenoid core descends correspondingly
and almost imperceptibly readjusts the carbons to their proper distance apart.
When the solenoid core descends so far as to release the screw tube this tube turns
slightly and thereby allows the spindle and carbon to descend but the consequent
diminution of the arc resistance and increased effective strength of the solenoid
cause the further turning of the screw tube to be instantly checked.
With care-
fully constructed mechanism and with carbons of good and uniform quality the
feeding action becomes practically continuous and in exact correspondence with
the rate of consumption of the carbons.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append two sheets of explanatory drawings
to be hereinafter referred to and representing modifications of my improved electric
arc lamps.
Figure, 1, on sheet 1, of the accompanying drawings is a plan and figure, 2, is a
sectional elevation of one modification of my improved lamp; whilst figure, 3, is
an inverted sectional plan of a detail. Figure, 4, on sheet 2, is a sectional elevation
of a second modification, and figures 5, and 7, show parts of two modifications
or variations, figure, 6, being an inverted sectional plan of a detail. In these
drawings the same reference numerals are used to mark the same or like parts
wherever they are repeated.
In the modification shown in figures 1, 2, and 3, the framing of the lamp is of
ordinary construction and comprises upper and lower crossheads, 7, 8, connected by
vertical side rods, 9, 10. The lower carbon, 11, is fixed in a socket in the bottom

page_text: crosshead, 8, which is insulated from one, 9, of the side rods, but in metallic
connection with the other side rod, 10, the latter being insulated from the top
crosshead, 7, and having a terminal, 12, fixed to it for the attachment of the
negative circuit wire.
The upper carbon, 13, is secured in a holder, 14, formed with lugs fitted to slide
on a pair of guide rods, 15, fixed to the top crosshead, 7, and having fixed to it a
screw spindle, 16, which is prevented from turning by the guide rods 15. The
screw spindle, 16, which is by preference made of brass or other non-magnetic
inetal passes up through a block or tube, 17, a part of which is formed with internal
screw threads fitting the threads of the spindle. The screw tube, 17, is fitted to
move vertically and to turn in a tubular guide or boss, 18, formed on the upper.
crosshead, 7, the downward movement of the screw tube being limited by a
collar, 19, formed on its upper part whilst its upward movement is limited by an
adjustable ring, 20, screwed upon its lower part. An enlarged top or head, 21, on
the screw tube, 17, is formed with fine teeth or grooves on its edge and underside
(as shown in figure 13) and there are arranged to engage with these teeth on [
diametrically opposite sides two knife edges, 22, (figure, 1) which are fixed to a
lever, 23, formed with a ring-shaped part encircling the screw tube, 17. The
lever, 23, is centered on a stud, 24, fixed to the upper crosshead, 7, and the free end
of the lever is jointed to the core, 25, of a solenoid, 26, also carried upon the
crosshead, 7. The positive wire of the circuit is to be attached to a terminal, 27,
connecting it to the solenoid, 26, and the other end of the solenoid (main) coil is to
be connected to the upper carbon, 13, either through the upper crosshead, 7, and
parts between it and the holder, 14, or by a flexible wire.
In the modification shown in figure, 4, the solenoid, 26, is placed centrally above
the carbons 13, 11, the core, 25, being made tubular for the spindle, 16, to pass up
through it. A pair of levers, 23, centered on studs, 24, are arranged on diametrically
opposite sides with their free ends engaging with the head, 21, of the screw
tube, 17, (this head, 21, being shown as of a slightly varied shape) and these levers
are acted on by arms 28, fixed to the bottom of the core, 25. In figure, 5, the parts
are shown as simplified by dispensing with the levers, 23, the core, 25, having fixed
to its lower end a fork, 29, formed or fitted with knife edges, 22, by means of which
it engages directly with the head, 21, of the screw tube, 17. The core, 25, and
fork 29, are prevented from turning by pins, 30, working in slots in the bracket 31,
which carries the solenoid, 26.
In the modification shown in figure, 7, the fork 29, fixed to the bottom of the
solenoid core, 25, is made without knife edges the parts for lifting the screw
tube, 17, being smooth. The screw tube, 17, is made with a collar, 32, having
angular notches formed in it and angular stops or knife edges, 33, are fixed to the
bracket, 31, in such positions as that when the screw tube, 17, is raised by the
solenoid core, 25, the notches of the collar, 32, engage with the stops, 33, and
prevent the screw tube from turning. An outer guide (18) for the screw tube, 17
is dispensed with.
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not restrict myself to the precise
details herein described or delineated but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is :-
1. The combination of parts constituting the electric arc lamp hereinbefore
described with reference to figures, 1, 2, and 3, of the accompanying drawings.
2. The modified combination of parts hereinbefore described with reference to
figure, 4, of the accompanying drawings.
3. The modified combination of parts herein before described with reference to
figure, 5, of the accompanying drawings.
4. The modified combination of parts hereinbefore described with reference to
figure, 7, of the accompanying drawings.
5. The combination of the screw spindle (16) screw tube (17) and an engaging

page_text: device arranged so as by one action of a solenoid or electro magnet to stop the
rotation of the screw tube and lift the tube and with it the screw spindle, the parts
being arranged and operating substantially as herein before described.
In Witness whereof I, the said, William Hopkin Akester have hereunto set
my hand and seal this twentieth day of November in the year of our
Lord One thousand eight hundred and eighty-two.
WILLIAM HOPKIN AKESTER. (L.S.)