Incandescent or Glow Lamps.
Year: 1885

page_text: Incandescent or Glow Lamps.
WILLIAM MAXWELL, Engineer 34 Claybrook Road S.W. THEOPHILUS VAUGHAN
HUGHES Associate of the Royal School of Mines Greenfield Mills, Holywell, North
Wales, do hereby declare the nature of our invention for IMPROVEMENTS IN
MERCURIAL AIR PUMPS FOR EXHAUSTING INCANDESCENT OR GLOW LAMPS to be
as follows:-
It is acknowledged at the present time that Mercurial Air Pumps of the Sprengel
type are the most efficient and reliable for obtaining the high vacua required in the
manufacture of Incandescent Lamps, but the slowness of its action when used in
the simple form is quite unsuited to the requirements of a manufactory; hence
various combinations with multiple "fall-tubes" have been designed to quicken
the process of exhaustion and to facilitate the transfer of mercury from the receiving
vessel to the supplying vessels of the pump, such combinations being chiefly
constructed of glass are both costly and fragile and therefore only contain a limited
number of" fall-tubes."
It is usual to connect such combinations with an auxiliary manual or automatic
air pump, and also to make use of the atmospheric pressure to effect the transfer
of the mercury from the lower to the higher level.
The object of our invention is to enable the number of fall tubes to be greatly
increased, to lessen the fragility and to combine therewith a suitable system for
the transfer of mercury from the receiving to the supplying vessels, without
exposing it to the dust or impurities prevalent in the atmosphere of a workroom―
and also to lessen the possibility of the diffusion of mercurial vapours through the
atmosphere of the workroom.
In carrying out our Invention we make use of a casing or chamber which may
be of cast-iron or any other suitable material and of any convenient or suitable
form furnished with valves or taps to admit and regulate the flow of the mercury
and air into the pump and also perforated for the admission of the "fall tubes."
Within the said casing or chamber a tube or vessel is placed or formed to
distribute the mercury to the "fall tubes." Above the said tube or vessel, trays
or cases containing absorbant and dessicating substances may also be placed. The
said casing or chamber with its contents and connections forms the head of the
pump.

page_text: A box or chamber similarly perforated and supplied with an exit tube for the
discharge of the mercury air et caetera forms the bottom of the pump.
The fall tubes pass into or through the perforations in the head and bottom
of the pump, and may be connected thereto by air-tight glands and cement.
The system for the transfer of the mercury from the receiving to the supplying
vessels consists of vessels or chambers placed at different levels with quitable
connections between each other and with the pumps, any one or all of which
said vessels or chambers may be connected with an exhaust pump or exhaust
chamber, and also with the atmosphere or other suitable medium of pressure by
means of suitable valves or taps. The said valves or taps are actuated by floats
placed within the chambers which rise or fall with any variation in the level of
the mercury and alternately or intermittently place the lower chambers in
connection with the pressure and exhaust.
The inflow of mercury into the lower chamber or chambers takes place during
the exhaust and the transfer from the lower to the upper chambers is effected by
the admission of atmospheric or other pressure.
Between the upper mercury supplying chamber and the pumps we insert an
automatic valve or regulator for the purpose of maintaining the head of mercury
constant in the pump or pumps.

page_text: Incandescent or Glow Lamps.
We WILLIAM MAXWELL, Engineer of 34 Claybrook Road SW and THEOPHILUS
VAUGHAN HUGHES, Associate of the Royal School of Mines, of Greenfield Mills
Holywell, North Wales, 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 exhausting vessels such as the bulbs of incandescent electric lamps, where a
very high degree of exhaustion is required, it is usual to begin the exhaustion by
the use of a mechanical air pump, and after a certain degree of exhaustion has
been thus attained, to carry the exhaustion still farther by means of apparatus
known as Sprengel or mercurial pumps. These consist of vertical glass tubes of
small bore open at the top to the exhausted vessel, and having their bottom
mouths dipping into mercury which forms a liquid seal for them. Mercury is
supplied in successive drops to the upper mouths of the tubos, and these drops.
form themselves into short columns that successively descend the tubes, each
column acting like a piston propelling down before it the small quantity of rare-
fied air that is interposed in the tube between it and the column that previously
descended. The air thus forced down each tube escapes at the bottom through
the mercury seal and is withdrawn by the mechanical air pump. Thus by using
a number of tubes through each of which a large number of mercury columns
successively descend, a very high degree of rarefaction can be attained in the upper
vessel from which the tubes descend or in a number of bulbs or other vessels that
are in communication with it. After a time, it is necessary to raise from the lower
compartment the quantity of mercury that has descended the tubes and to restore
it as a supply to the upper compartment to be ready to feed the tubes again. It
has been proposed to effect this raising of the mercury by the pressure of the
atmosphere, and apparatus consisting mostly of glass has been sometimes made to
act in this way, but, owing to the complexity and fragility of such apparatus, they
have not become practically so useful as might be desired. Our invention relates
to a construction and arrangement of apparatus for operating in this manner such
that strong durable material, chiefly iron is employed in its structure, and all parts
can without difficulty be made and maintained sound and tight. We will describe
apparatus according to our invention, referring to the accompanying drawings.
Fig. 1 is a vertical section of a set of Sprengel or mercurial pumps, of which
there may be many arranged in a row. Fig. 2 is an enlarged section of two of the
mercurial tubes of Fig. 1. Fig. 3 is a vertical section of the apparatus for raising.
the mercury from the lower to the higher level.
Referring first to Figs. 1 and 2, A are the mercury tubes, the upper ends of
which pass through packings a in holes in the bottom of an upper compartment B,
these holes and the mouths of the tubes being funnel shaped. The lower ends
of the tubes also pass through packings in holes in the upper side of a lower
compartment C, and extend down rather more than midway in the depth of C.
'

page_text: In the compartment B there is an interior vessel D containing mercury, this vessel
not fitting exactly within B but leaving around it free passage from the upper
part of B to the space under D, for air coming by a pipe E from a set of lamp
bulbs or other vessels that have to be exhausted, such air being preferably dried
on its way to D by being passed over absorbent materials in the usual way.
Through the bottom of the vessel D there are small holes d one for each of the
tubes A immediately over some part of the annular space surrounding the tube.
At one end of the compartment C there is a plug sluice c which can be raised or
lowered by a screw, so as to keep a certain level of mercury in C or when the plug
is lowered quite down to let it all flow into a passage F. From the compartment
a pipe G communicates with a vacuum pipe V exhausted by a mechanical pump.
As mercury, issues in minute streams or successive drops through one of the holes d,
it fills the conical annular space around the top of the tube A and assumes a convex
surface as shewn in Fig. 2, after which a quantity of it overflows into the funnel
mouth of the tube, and descends like a fluid piston propelling before it such air as
was in the tube. The air thus forced down the tube bubbles through the mercury
in C and passes away by the pipe G. This action is repented in each of the
tubes A. It is to be understood that there may be a number of sets of the
apparatus shewn in Fig. 1 arranged in a row all having their upper compartments B
in communication with a supply pipe H and having their lower compartments C in
communication with a discharge passage F. The passage F communicates by a
pipe with the lower compartment K of the raising apparatus shewn in Fig. 3, and
the pipe H communicates by a pipe h with the upper compartment L, and the two
compartments K and L communicate by a vertical pipe M. At the mouth of the
pipe there is a valve fl which prevents back flow of mercury from K to F. In
the passage from H to D (Fig. 1) there is a check valve 6 held down by a light
spring to prevent return of mercury from D. At the bottom of the pipe M
(Fig. 3) there is a check valve m to prevent back flow down the pipe M. The
compartment L communicates by a pipe with the vacuum pipe V, so that in Las
well as in F a partial vacuum is maintained. The mouth of the pipe h is fitted
with a valve h³ which is attached to the stem of a piston h¹, having projecting
down from it a rim h¹ with holes through it. When the piston h¹ is down as
shewn in Fig. 3 the pipe h being then closed by the valve h³, the holes in the
rim h³ coincide with holes in the cylindrical casing of the piston ¹ and mercury
can thus flow into the space under the piston. When the piston h¹ floats up it
opens the valve h³ allowing mercury to pass by the pipe h to H, but at the same
time as the rim h³ rises with the piston the passages from L are more or less closed,
and only a portion of the mercury can pass to H. In this way the vessel D
continues to be fed with mercury. In the compartment K there is a float k free
to slide up or down on a rod N having on it two collars n n. When the float
rising meets the upper collar n and still farther rises, it raises the rod N, and when
the float descending meets the lower collar n and still farther descends it lowers
the rod N. At the top of N are formed notches in which engages the one or the
other of the two spring studs o and o¹, exerting some force to hold the rod in either
its raised or lowered position, but not sufficient or resist the action of the float k
in raising or lowering the rod. As shewn in Fig. 3 the rod N is in its lowest
position in which it is held by the spring stud o. The rod N has two grooves cut
circularly round it at p and q which when N is down coincide with passages
namely p¹ communicating with the vacuum pipe V, and q¹ which is open to the
air. When N is raised, p coincides with a passage p² leading to the open air,
and with a passage q³ leading to the vacuum pipe V. Thus N operates as a slide
valve putting the two sides of a piston P alternately in communication with the
air and the vacuum. As shewn in Fig. 3 the piston P is kept down by the
atmospheric pressure above it communicated by q¹ caused by the vacuum below
communicated by p¹, and while the piston is in this position a valve r at the
lower end of its stem is closed but a valve at the upper end is open so that
the vessel K is in communication with the vacuum pipe V, and mercury from the

page_text: channel F flows into it. When the float k acting on the upper collar n raises the
rod N the ports p¹ p³ and q¹ qª become alternated and the piston P is now subjected
to the pressure of the atmosphere on its underside and to vacuum on its upper
side. The piston P thereupon rises closing the valve rand opening r also
uncovering a side opening 8, by which air enters and pressing on the mercury in K
causes it to flow up the pipe M to the upper compartment L.
When the
compartment K is thus emptied the float k again pressing on the lower collar n
lowers the rod N and restores the parts to the condition shewn in Fig. 3.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim in respect of mercurial air pumps for exhaustion, is :—
1. In combination with a mechanical exhausting pump, a set of mercurial
exhaust tubes or several sets of these constructed and arranged substantially as
described with reference to Figs. 1 and 2, and a mercury raising apparatus
constructed and arranged substantially as described with reference to Fig. 3 of the
accompanying drawings.
2. A mercurial exhaust tube A having its upper mouth funnelled and held in
a funnelled hole under a mercury vessel perforated at bottom, and having its
lower mouth immersed in mercury.
.3. In combination with a number of exhaust tubes A, an upper compartment B
which contains a mercury vessel D and is connected by a pipe E with vessels under
exhaustion, and a lower compartiment C which contains mercury maintained at
desired level by an adjustable sluice plug c, and is connected by a pipe G with a
vacuum pipe V.
4. A mercury raising apparatus consisting of a lower compartment K provided
with float valve apparatus, and an upper compartment L connected with K by
a pipe M.
5. In the lower compartment K a float valve apparatus consisting of a float k
rod N with its collars n and grooves p q governing ports p¹ p² q¹ q², in combination
with piston P and its valves r', air port & and vacuum pipe V.
6. In the upper compartment L the float piston h¹ with its rim h³ and valve h³
in combination with the supply pipe h.