Improvements in Means for Conducting Electricity for Electric Lighting and other Purposes.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Means for Conducting Electricity for Electric
Lighting and other Purposes.
I, MARTHA W. POLLARD, of 113 Otis Street East Cambridge, Massachusetts,
n the United States of America, do hereby declare the nature of this invention
nd in what manner the same is to be performed, to be particularly described and
scertained in and by the following statement :—
The object of my invention is to provide a simple and improved means for
conducting electricity for electric lighting and other purposes. The invention is
particularly adapted for use in connection with incandescent electric lamps and
I have described it in connection with such a lamp and illustrated it in the
accompanying drawing, in which :-
Figure 1 is a central vertical section of a lamp embodying my invention.
Figure 1 is a view a quarter turn from Figure 1 with the bulb removed.
Figures 2, 3 and 4 are modifications.
Figure 5 is a section on line x a Figure 1.
In the drawing 1 represents the globe of an incandescent electric lamp of the
ordinary or any desired construction, and 2 a short section of tube formed
within or united to the neck of the globe and hermetically sealed in the ordinary
manner. 3, 3 represent the glass tubes which support the carbon filament 4, and
through which electrical connection is made with the conducting wires 5, 5 as
hereinafter described.
Heretofore, so far as I am aware, the only practical manner of connecting the
filament with the conducting wires has been by means of short sections of platinum
wire passing through the tubes which are compressed around the wires while the
glass is not to form a seal to prevent the admission of air to the bulb or globe.
This method is not satisfactory however as it is difficult to maintain a perfect seal
for any considerable length of time between the wires and glass. I have found that
by depositing upon glass a line of silver, gold, platinum or other metal in powdered
form, and then heating the glass sufficiently to cause the metal to adhere to it, the
line of minute particles thus united with or embedded in the surface of the glass
will form a conductor for the electric current.
In embodying this principle in a lamp, I find it desirable to coat the interior
surface of the tubes 3, 3 with size suitably adapted for the purpose, and upon this
size to sprinkle or deposit fine silver powder, after which the tubes are heated
sufficiently to cause the particles of silver to adhere firmly to the glass, the size
serving to hold the powder in position upon the glass until the glass is raised to the
temperature necessary to cause the powder to adhere thereto or become embedded
therein. While the glass is hot I pinch or compress each tube until its opposite
walls come in contact and become welded together, thus forming a seal which will
maintain a vacuum in the globe when the air therein has been exhausted. The ends
of the carbon filament can be attached within the ends of the glass tubes by any of
the carbon pastes well known to those skilled in the art, or may be held by any of
the plating processes so well known. The conducting wires 5, 5 may be connected
by cold pinching them within the tubes 3, 3 having the wire in contact with the
silver, as shewn in Figure 1. In a lamp thus formed the minute particles of silver
or other metal unite with or become embedded firmly in the glass, and the seal
formed by pinching the tube and forcing its opposite faces together while the glass
is hot is perfect, and all liability of the entrance of air is removed. At the same
time the silver particles thus united with the glass form a conducting connection
between the conducting wires and the carbon filament. Instead of sealing the

page_text: cane, may
tubes 3 by pinching, as shewn in Figure 1, a pin of solid glass 10 called c
be inserted into each tube, as shewn in Figure 2 after the silver has been fused in
place, and the inner walls of the tube welded by heat upon the cane.
•
In Figure 3, I have shewn a modification in which the smaller tubes 3, 3 are
dispensed with. The tube 2 has formed within it upon sides opposite to each other
two strips or deposits of silver 6,6 extending the entire length of the tube. The
tube is pinched near its lower end as, at 7, to form the seal, and the portion of
the end of the tube between the strips of silver is also compressed as at 8, thus
leaving two recesses or indentations 9, 9 into which the ends of the filament may
be secured in contact with the silver as above described. The conducting wires
are placed within the upper end of the tube, as shewn, and are held in contact
with the silver on each side by a non-conducting plug 11.
I
Instead of placing the deposits upon the inside of the tube 2, I may, if desired,
form the tube 2 closed at one end, and apply the silver or other metal upon the
outside as shewn in Figure 4, the conductor in this case passing through the joint,
between the tube and the neck of the bulb or globe, which forms the seal. When
this form is used the wires and filaments are in communication with the conducting
strips 6, and upon the outer side of the tube, being secured in any suitable way, the
walls of the tube intervening between the ends of the wire to serve as a non-
conductor.
It will be understood that though I have described silver as the conductor used,
almost any metal may be used. I prefer silver as it is easily reduced to a fine
powder. I find the best method of doing this to be to dissolve the silver in nitric
acid and then suspend pieces of copper in the solution to cast down the silver in a
very fine powder. Upon removing the silver from the bottom of the solution it
should be washed thoroughly and passed through a very fine sieve. If desired the
metal may be applied in the form of a very thin leaf instead of powder.
The size used to attach the dust or powder to the glass may be made by mixing
together copaiva balsam (two parts) and fir balsam (one part) or any of the other
sizes may be used as desired..
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. The herein described method of forming a conducting seal for incandescent
lamps, consisting in depositing powdered silver or other metal upon the filament
supporting tube or tubes, heating the glass to cause the metal to become fused upon
or embedded in the glass, and then bringing the adjacent edges of the glass together
while hot to form the seal, substantially as described.
2. The described method of forming a conducting seal for incandescent lamps
consisting in depositing metallic powder or leaf upon the interior of the filament
supporting tube or tubes, heating the glass to fuse the powder or leaf thereon, and
finally pinching the walls of the tube together while hot to form the seal, substan-
tially as described.
3. The described method of forming a sealed conductor for incandescent lamps
consisting in depositing two lines of metallic powder or leaf upon the interior of the
filament supporting tube or tubes, heating the glass to cause the powder to adhere
thereto, pinching the lower portion of the tube while hot to form the seal, and
compressing the portion of the tube between the strips of powder to form seats or
recesses for the ends of the filament, substantially as described.
4. The described method of forming a sealed conductor for incandescent lamps
consisting in painting a line of size upon the tube or tubes, depositing thereon
powdered silver, heating the glass to cause the powder to adhere thereto, and
uniting the opposite faces of the glass while hot to form a seal, substantially
as described.
5. In combination, with the filament supporting tube closed to form a seal, two
bands or deposits of silver or other metal upon the said tube extending through the

page_text: seal and forming an electrical connection between the filament and conducting wires,
substantially as described.
6. In combination with the sealed supporting tubes 3, 3 of an incandescent lamp,
a filament supported in the lower ends thereof, conducting wires leading to the upper
portions of the said tubes, and a conducting medium for conveying the current from
the conducting wires to the filament consisting of powdered silver or other metal
within the tubes and extending through the seal, substantially as described.
Dated this 1st day of November 1892.
G. F. REDFERN & Co.,
"
4, South Street, Finsbury, London, Agents for the Applicant.