IMPROVEMENTS IN AND CONNECTED WITH AIR EXHAUSTING APPARATUS. TO .BE USED IN PREPARING INCANDESCENT ELECTRIC LAMPS دو
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 AND CONNECTED WITH AIR EXHAUSTING APPARATUS. TO
.BE USED IN PREPARING INCANDESCENT ELECTRIC LAMPS
دو
PROVISIONAL SPECIFICATION left by the said William Hopkin Akester at
the Office of the Commissioners of Patents on the 27th May 1882.
WILLIAM HOPKIN AKESTER, of Glasgow, in the County of Lanark, North
Britain, Electrician and Engineer, "IMPROVEMENTS IN AND CONNECTED WITH
AIR EXHAUSTING APPARATUS TO BE USED IN PREPARING INCANDESCENT ELECTRIC
LAMPS
"
This Invention relates to what are known as incandescent electric lamps in
which the light is produced by the passage of an electric current through a strip
of carbon in a glass bulb or vessel in which there is a vacuum, the object of the
Invention being to improve the arrangements and apparatus by which the vacuum
is obtained.
In carrying out the Invention mercury is employed and as it enters the apparatus
connected with the bulbs at a high level and is withdrawn from it at a low level a
pump of special construction is employed to raise it from the low level back again
to the high level. From its nature mercury is extremely difficult to deal with in
pumping apparatus, and it is difficult to avoid concussive action which causes
leakages through joints and stuffing boxes. In one modification of the improved
pump there are only two valves and a single, stuffing box. A hollow plunger is
used with an ordinary conical-seated check valve at its bottom, and this plunger
works through a stuffing box into a barrel which has a similar check valve at its
bottom. The pump barrel is placed at a low enough level for the mercury to run
into it from the low level of the exhausting apparatus, and the plunger is continued
up by a pipe which extends up a little above the highest level to which the mercury
has to be raised, and at the top of the plunger pipe it is bent and continued with

page_text: .
a little inclination into a cistern. The stuffing box of the pump barrel may be at
the top of the barrel itself or at the top of a pipe extending upwards with the
plunger pipe passing up through it so as to be subjected to diminished pressure; or
the stuffing box may be dispensed with if the outer pipe is extended high enough
and if the barrel is at a sufficiently low level, there being in this modification
a stationary upper rod over which the plunger pipe works and which causes
the displacement and discharge of the mercury lifted by the plunger pipe when
it rises.
The cistern into which the pump delivers the mercury is provided with an
overflow so that if the pump continues to work without the mercury being used it
will not become empty but will pump over again what overflows. The first cistern
supplies a second cistern through a stopcock worked by a float, so that the mercury
in the second cistern is maintained approximately at a constant level. The second
cistern is connected to a horizontal main supply pipe which is at the low level, and
is fitted with branch pipes for the several exhausters of a series. A second
horizontal pipe which may be termed the discharge main has also branches
connected to the exhausters and leads the mercury. from them to the elevating
pump. At the bottom of each exhauster there is a three-way cock for shutting off
the exhauster or for putting it in communication with either the supply main or
the discharge main, and the latter is made with a siphon bend to prevent the level
in the exhausters from getting below a point which is a little above the stopcocks.
Each exhauster consists of two vertical lengths of tubing by preference of glass, the
upper length having the lamp bulb connected to it by passing its temporary tube
through a tubular rubber plug in the open top of the tube length. The upper tube
length is connected to the lower tube length at a point about 32 inches above the
lower level and is continued up to a point a little higher than the level of the lower
cistern; whilst the upper length extends about 32 inches higher than the same level.
A valve is fitted to the open top of the lower tube length. When an exhauster is
in communication with the supply main the mercury rising in the tube lengths
expels from the lower one all the air above the connection with the higher length.
The stopcock being then turned to open communication with the discharge main
the mercury in sinking draws air out of the lamp bulb into the lower tube length
whence the air is expelled by admitting mercury again; and the admission and
withdrawal of mercury are repeated until the exhaustion of the lamp bulb is
considered sufficient. The stopcocks of a series of exhausters are fitted with
mechanism for turning all or sections of them simultaneously.

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
27th November 1882.
WILLIAM HOPKIN AKESTER, of Glasgow, in the County of Lanark, North
Britain, Electrician and Engineer, " IMPROVEMENTS IN AND CONNECTED WITH
AIR-EXHAUSTING APPARATUS TO BE USED IN PREPARING INCANDESCENT ELECTRIC
LAMPS
"
My said Invention relates to what are known as incandescent electric lamps in
which the light is produced by the passage of an electric current through a strip of
carbon in a glass bulb or vessel in which there is a vacuum, the object of my
Invention being to improve the arrangements and apparatus by which the vacuum
is obtained.
In carrying out my Invention mercury is employed and as it enters the apparatus
connected with the bulbs at a high level, and is withdrawn from it at a low level,
a pump of special construction is employed to raise it from the low level back
again to the high level. From its nature, and particularly from its great specific
gravity, mercury is extremely difficult to deal with in pumping apparatus, and it
is difficult to avoid concussive action which causes leakages through joints and
stuffing boxes. In one modification of my improved pump there are only two
valves and a single stuffing box, and in another modification one of these valves
and the stuffing box are dispensed with. A hollow plunger is used with an
ordinary conical-seated check valve at its bottom, and the plunger is continued up
by a pipe which extends up a little above the highest level to which the mercury
has to be raised, and which discharges from its upper end into a first or higher
cistern provided with an overflow so that if the pump continues to work without
the mercury being used it will not become empty but will pump over again what
overflows. The first cistern supplies a second lower cistern through a stopcock
worked by a float, so that the mercury in the second cistern is maintained approxi-
mately at a constant level. The second cistern is connected to a horizontal main
supply pipe which is at the low level and is fitted with branch pipes for the several
exhausters of a series. A second horizontal pipe which may be termed the
discharge main has also branches connected to the exhausters and leads the
mercury from them to the elevating pump. The several branch pipes are controlled
by stopcocks there being a separate one on each branch pipe or a single three-way
stopcock to each pair of branches. The several stopcocks appertaining to a series
of exhausters may have mechanism applied to move them or sections of them
simultaneously, or a single three-way stopcock or pair of separate stopcocks may
be arranged in connection with two or more exhausters.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append a sheet of explanatory drawings
to be hereinafter referred to and representing modifications of my improved
apparatus.
Figure 1, on the accompanying sheet of drawings is an elevation of one modifi-
cation of my improved apparatus, and figure, 2, is a side elevation of a detail.
Figure, 3, is an enlarged vertical section of one modification of the pump for
elevating the mercury and figure, 4, is a similar section of a second modification.
In these drawings the same reference numerals are used to mark the same or like
parts wherever they are repeated.
The apparatus shown in figure, 1, is designed for operating in connection with a
series of exhausters, but only one of these is shown. Each exhauster comprises an

page_text: upper glass tube, 5, made with an enlargement at the top to receive the temporary
stem of the bulb to be exhausted, this upper tube, 5, having its lower end connected
in an airtight manner to a branch, 6, formed on the side of a lower and larger
glass tube, 7, 8. The upper part, 7, of the lower tube is open at its top but is made
with a contraction which is ground internally to form a seat for a glass check
valve, 9;
and the lower part, 8, of the tube which extends at least 32 inches below
the connection of the side branch, 6, has its bottom end cemented into the nozzle
of a three-way cock, 10. This three-way cock has connected to it branch pipes,
11, 12, from two horizontal pipes 13, 14, which are the supply and discharge mains
for the mercury.
When the three-way cock, 10, is set to admit mercury the
mercury rises in the tube 8, 7, and expels air past the valve, 9, and when the cock
is set to discharge, the descent of the mercury causes air to be drawn from the bulb
by the upper tube, 5, and side branch, 6, into the lower tube, 7, 8. The mercury
is admitted and discharged repeatedly and at each admission expels past the
valve, 9, all the air in the upper part, 7, of the lower tube. As the vacuum
becomes more perfect the mercury when admitted rises more and more up the
upper tube, 5, its height therein above the level of the supplying cistern indi-
cating the degree of vacuum, the tube, 5, extending at least 32 inches above
that level.
The supply main, 13, is connected by a vertical pipe, 15, fitted with a stopcock
to a cistern, 16, which cistern receives its supply from a higher cistern, 17, through
a pipe, 19, having a stopcock controlled by. a float, 20, in the lower cistern, 16. A
uniform level is thus approximately maintained in the lower cistern, 16, and it is
arranged to have this level a little above that of the seat of the valve, 9, past which
the air is expelled from the exhauster.
The discharge main, 14, is connected through a siphon bend, 21, with a vessel, 22,
fixed to the bottom of the barrel, 23, of the elevating pump. The siphon bend, 21,
is to prevent the mercury being all run out of the main, 14, and it is fitted with an
air pipe, 24, to prevent siphon action in the event of air having access to the
main, 14. As however it may be sometimes necessary to run off the mercury from
the main, 14, a by-pass pipe and stopcock, 25, is provided to allow of that being
done. At the bottom of the pump barrel, 23, there is a foot valve, 25, (figure, 3).
fitted to a tube, 26, dipping nearly to the bottom of the vessel, 22, so as to draw
mercury even when there is only a small quantity in the vessel. The pump barrel
is fitted with a stuffing box, 27, through which there works a hollow plunger, 28,
fitted with a check valve, 29, at its bottom end; and this plunger, 28, is worked
by means of a forked connecting rod, 30, from a crank, 31, on an overhead rotating
shaft driven in any convenient way. A pipe, 32, is connected to the hollow
plunger, 28, and its upper end is bent and has attached to it a piece of flexible
tubing, 33, leading into the upper cistern, 17. This cistern is provided with an
overflow pipe, 18, leading to the lower vessel, 22.
The stuffing box (27) of the pump barrel may be at the top of the barrel or of a
pipe fixed thereto such barrel or pipe being extended considerably upwards with
the plunger pipe, 32, passing up through it so as to be subjected to diminished
pressure; or the stuffing box may be dispensed with if the outer pipe is extended
high enough and if the barrel is placed at a sufficiently low level, the parts being
in this case arranged as shown in figure 4. In this modification the hollow
plunger, 28, is arranged to descend nearly to the bottom of the vessel, 22, into
which the mercury drains from the discharge main, 14, and on the top of the
vessel 22, there is fixed a long barrel or pipe, 34, extending up to the overflow
level of the upper cistern, 17, which cistern is in this example formed or fixed so
as to encircle the top of the pipe, 34. The hollow plunger, 28, does not require to
work tightly in the barrel or pipe, 34, and the overflow from the cistern may take
place down between the plunger, 28, and the pipe, 34, or down a groove formed in
either of them. The plunger, 28, works upon an inner stationary bar, 35, fixed to
a bridge piece, 36, spanning the cistern, 17, and this bar, 35, may either be a good
but easy fit to the inside of the plunger, 28, in which case a groove, 37, is formed

page_text: in it for the passage upwards of the mercury, or it may be made sufficiently
smaller than the bore of the plunger to allow the mercury to pass up between.
The plunger, 28, is worked by a connecting rod 30, from a rotating crank as in the
other modification, and when in its lowest position the mercury flows by gravitation
into the internal space below the bar, 35. Then when the plunger is drawn up the
check valve, 29, prevents the return of the mercury, and it is compelled to pass up
the groove, 37, from the top of which it issues into the cistern, 17.
My improved general arrangement of the apparatus for supplying the mercury
to and discharging it from the exhausters may be used with other appliances for
elevating the mercury instead of the improved pumps herein before described,
for example with an inclined hollow Archimedian screw or with an endless chain
of buckets.
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 apparatus for supplying mercury to and withdrawing it
from exhausters used in preparing incandescent electric lamps, such combination
consisting of the upper and lower cisterns (17, 16) the supply and discharge mains
(13, 14) with their branch connections and stopcocks for the several exhausters of
a series or each set for two or more exhausters, and apparatus for elevating the
mercury to the upper cistern, all substantially as hereinbefore described.
2. The improved construction of pump for elevating mercury for use in pre-
paring incandescent electric lamps herein before described with reference to figures,
1, and 3, of the accompanying drawings.
3. The improved construction of pump for elevating mercury for use in preparing
incandescent electric lamps herein before described with reference to figure, 4, of the
accompanying drawings.
In Witness whereof, I, the said William Hopkin Akester have hereunto set
my hand and seal this twenty-third day of November in the year of our
Lord One thousand eight hundred and eighty-two.
Witness
EDMUND HUNT
Patent Agent
Glasgow
WILLIAM HOPKIN AKESTER, (L.S.)