IMPROVEMENTS IN THE MEANS EMPLOYED FOR CREATING A VACUUM IN THE BULBS OF INCANDESCENT ELECTRIC LAMPS
Year: 1883

page_text: LETTERS PATENT to Charles Henry Stearn of Forest Hill in the County of
Surrey for an Invention of "IMPROVEMENTS IN THE MEANS EMPLOYED FOR
CREATING A VACUUM IN THE BULBS OF INCANDESCENT ELECTRIC LAMPS"
PROVISIONAL SPECIFICATION left by the said Charles Henry Stearn at
the Office of the Commissioners of Patents on the 15th June 1888.
CHARLES HENRY STEARN of Forest Hill in the County of Surrey " IMPROVE-
MENTS IN THE MEANS EMPLOYED FOR CREATING A VACUUM IN THE BULBS OF
INCANDESCENT ELECTRIC LAMPS
33
My said Invention has for its object to provide an effectual and convenient
means for producing a permanent high vacuum in the bulbs of incandescent
electric lamps. According to my said invention I enclose the bulb in which the
vacuum is to be created in a casing box or covering made of asbestos or other
non-conductor or slow conductor of heat, which casing box or covering may or
may not fit closely to the bulb. For example it may consist of a base or
platform with orifices for the tube through which the exhaustion is effected and
for the conducting wires to pass through and of a cap cover or box which is placed
over the bulb and rests upon the said base or platform.
The bulb being enclosed in the said casing box or covering is connected to the
exhausting apparatus and when during the final exhaustion a current of electricity
is passed through the filament of the lamp the said Casing box or covering retains
the heat so that the bulb rapidly acquires and retains a high temperature during
the said final exhaustion which enables a very high and perfect permanent vacuum
to be created in the bulb.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Henry Stearn in the Great Seal Patent Office on the 15th
December 1883.
IMPROVE-
MENTS IN THE MEANS EMPLOYED FOR CREATING A VACUUM IN THE BULBS OF
INCANDESCENT ELECTRIC LAMPS
CHARLES HENRY STEARN of Forest Hill in the County of Surrey
"
My said Invention has for its object to provide an effectual and convenient
means for producing a permanent high vacuum in the bulbs of incandescent
electric lamps. According-to-my-said Invention I enclose the bulb in which the
vacuum is to be created in a casing, box, covering, enclosure-or-envelope, made of
asbestos or other non-conductor or bad conductor of heat, which casing, box or
covering may or may not fit closely to the bulb. For example, it may consist of
a base or platform with orifices for the tube through which the exhaustion is
effected and for the conducting wires to pass through and of a cap cover or box
which is placed over the bulb and rests upon the said base or platform.
connected to the
The bulb being enclosed in the said casing box or covering
exhausting apparatus and when during the final exhaustion a current of Electricity
is passed through the filament of the lamp the said casing box or covering retains
the heat so that the bulb rapidly acquires and retains a high temperature
during the said final exhaustion which enables a very high and perfect permanent
vacuum to be created in the bulb.
And in order that my said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer
to the annexed drawing.
On the said drawing A represents a platform consisting of or covered with
asbestos or other non-conductor or bad conductor of heat forming a support
through which the conducting wires w, w, (to the filament or filaments) and also
the stem c, of the bulb pass-B represents the casing box. or covering formed of
or lined with asbestos or other non-conductor or bad conductor of heat and placed
over the bulb and resting on the platform A or fastened thereto by any suitable
means The heating by the passage of electricity through the filament or filaments
may be supplemented by a gas burner or other heater situated inside the
casing box or covering or the heating may be effected by this latter means alone.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the sano is or may be used or carried into
effect I would observe in conclusion that I do not limit myself to the precise
details herein before described and shewn in the drawing as the same may be
varied without departing from the nature of my luvention but what I consider
to be novel and original and therefore claim as the Invention secured to me by
the herein before in part recited Letters Patent is :-
In creating a vacuum in the bulbs of incandescent Electric lamps the employment
of a casing, box, covering, enclosure or envelope of asbestos or other non-conducting
or bad conducting material substantially as and for the purpose herein before
described.
In witness whereof I the said Charles Henry Stearn have to this my
Specification set my hand and seal this thirteenth day of December one thousand
eight hundred and eighty three.