Improvements in Electric Lamps.
Year: 1899

page_text: Date of Application, 20th Mar., 1899
Complete Specification Left, 20th Dec., 1899-Accepted, 10th Mar., 1900
PROVISIONAL SPECIFICATION.
Improvements in Electric Lamps.
1, SERGE BERDITSCHEWSKY-APOSTOLOFF, of 5, Fenchurch Street, in the City of
London, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to means of applying and protecting a light refracting and
diffusing medium for electric lamps consisting of a spirally wound rod of glass
as described in the specification of a previous patent.
The invention consists in enclosing the spiral applied externally of the lamp
bulb, within an outer bulb formed of glass or other translucent material the outer
bulb being formed of two separate parts united after application about the spiral
by means of a silicate, Canada balsam or other suitable cement or by a band of
plastic glass. The spiral is made in two parts corresponding to the upper and
lower hemispheres of the lamp bulb and the outer envelope is also made in two
parts, the upper part being adapted to pass over the head of the lamp and to be
firmly secured by a collar screwing thereon, the outer bulb closely enveloping the
spiral so as both to hold it in place, protect it from dust and injury and enable
the lamp to be handled and to be fitted in or removed from its holder without
injuring the spiral.
Ta thith Joy of March 1899.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
I, SERGE BERDITSCHLEWSKY-APOSTOLOFF, of 5, Fenchurch Street, in the City of
of London, Engineer, 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:-
This invention relates to means of combining, with an electric incandescence
lamp, a light refracting and diffusing medium composed of a glass rod spirally
wound so as to form an envelope surrounding the bulb and screening the fila-
ment; and the invention consists in enclosing said medium within an outer
protective globe applied to the lamp in such manner that the lamp so enclosed
may be handled as a single piece and be fixed to the lamp socket or removed
therefrom with the same facility as an ordinary incandescence lamp having an
uncovered bulb whilst the light refracting and diffusing medium is completely

page_text: protected against injury and when the lamp is worn out is, together with the
protective outer globe, available for use with an indefinite succession of lamps.
The lamp itself would preferably be one having a bulb of cylindrical form in
order to facilitate its introduction into, and removal from, the globe and the
refracting envelope, but the lamp may have a bulb of spherical, pear-shaped, or
other form if so desired. In any case the outer globe is made in halves of sub-
stantially hemi-spherical form united along their meeting edges. In the case of
a lamp whose bulb is cylindrical, or of a diameter not materially greater than
that of the cap, the junction is preferably a permanent one, since the form of
the bulb permits of its being introduced into, and withdrawn from, the globe and
envelope through an opening provided for the purpose in the top of the latter.
In the case however of a lamp having a spherical or otherwise shaped bulb (or a
bulb whose diameter considerably exceeds that of the cap) such a lamp cannot
conveniently be so introduced into, or removed from, the globe and refracting
envelope which must therefore be applied to the lamp from opposite ends; and
in this case the joint between the halves of the globe is closed by means of a
locking device adapted to be secured after the lamp bulb and its cap have been
inserted from below and adjusted in position in the upper half of the globe.
The refracting envelope of spirally-wound glass rod would usually be made in
halves which, in the latter of the two cases just described, would be separabie,
but in the former case may be permanently united to form one continuous spiral
before being enclosed within the outer globe.
Reference is to be had to the accompanying drawings forming part of this
specification wherein Figure 1 is a side elevation partly in section, illustrating
the invention as applied to an incandescence electric lamp having a spherical
bulb. Figure 2 is a similar view illustrating the invention as applied to a lamp
having a cylindrical bulb. Figure 3 is a separate view of the light-refracting
and diffusing medium with the enclosing globe, as used with a cylindrical lamp,
the lamp itself being omitted. Figures 4 and 5 are cross sectional and face
views (drawn to an enlarged scale) of a portion of the outer globe, illustrating a
mode of jointing the separate parts together.
Referring to Figure 1, a is the spherical bulb of an incandescence lamp of
which is the metal cap as usual. The light-refracting and diffusing medium
consists of an envelope formed of a spirally-wound rod of glass, made in separate
halves c¹, ², corresponding to the upper and lower hemispheres of the lamp bulb
and together constituting a continuous spiral adapted in the case of a spherical
bulb to lie close to the bulb a of the lamp, the upper half of the spiral having
an axial aperture to give passage to the cap b of the lamp whilst the lower half
is adapted to be centred on the point d of the lamp bulb so as to be held steadily
in position.
The outer protective covering consists of a globe of glass, (or other suitable
translucent material) of a size to closely surround the glass spiral and is made in
two parts e, ², corresponding to those of the spiral envelope c¹, c². The upper
parte is formed with a neck f upon which is cemented a metal ferrule g adapted
to fit over the cap of the lamp and the lower part is preferably formed with
a central concave nipple to accommodate the projecting point d of the bulb,
whilst permitting the body of the globe to lie close up to and support the spiral
throughout practically its whole extent. The two parts el and e² of the globe may
be secured to one another by any suitable kind of joint so as to form either a
temporary or permanent closure." In view of the fact that it is desirable to
preserve the refracting medium and outer globe intact for future use after
removal from a worn-out lamp, the joint e is made detachable in the case of a
lamp having a spherical bulb, for which purpose the two parts e¹, e², of the globe
may be provided with metal rims h¹, h2, lapped around (and secured with suitable
cement to) their meeting edges as. shewn more clearly in the enlarged views
Figures 4 and 5, the one rim (as h¹,) carrying two or more pins i adapted to enter
and engage with keyhole slots in the other rim..

page_text: The mode of applying the refracting medium and outer globe to the lamp is as
follows: The upper half c of the spiral envelope is passed over the cap of the
lamp so as to rest on the shoulders of the bulb a. The upper part e¹ of the outer
globe is then passed over the cap in the same way so as to enclose the spiral c¹,
and is secured in position by means of two or more metal tongues & stamped out
from or attached to the cap b, the tongues being bent outwards and downwards
over the upper end of the ferrule g so as to prevent separation of this part of the
globe from the lamp, the tongues engaging between the sides of notches in the
upstanding portion m of the ferrule g so that when the lamp is grasped for the
purpose of rotating the lamp when fitting the latter into, or removing it from,
The lower
its socket the envelope and lamp are caused to turn together as one.
half of the spiral is now placed over the lower hemisphere of the lamp bulb a
and the corresponding part of the outer globe is fixed in place by means of the
pin and slot-locking device above described or otherwise, when the lamp is ready
A strip of metal foil, paper, or other material may if desired be pasted
over the joint e between the halves e, e², of the globe for the purpose of excluding
dust and preventing the unauthorized removal of the envelope.
for use.
It will be observed that when the invention is applied to a lamp having a bulb
of spherical or other shape whose equatorial diameter is large relatively to that
of the cap, as in the case illustrated in Figure 1, it is necessary that the two
halves of the spiral envelope and also those of the outer globe, should be separable
owing to the fact that both the spiral and globe must necessarily be superposed
upon the lamp bulb in separate halves and from opposite ends as above described
and must be removed from the lamp in like manner.
Figures 2 and 3 illustrate an arrangement of spiral envelope and globe
applicable to a lamp having a cylindrical bulb the use of which enables the spiral
and globe to be built up independently of the lamp so as to form one integral
structure which is complete in itself and may be applied to, or removed from, the
lamp. without separation of the component parts of such structure. In Figure 2, al
is the cylindrical bulb of the lamp, being the cap. The refracting medium is
composed as before of a glass rod spirally-wound so as to form a sphere, the
spiral being either .continuous or in halves to suit the convenience of manu-
facture, the two parts being in the latter case preferably united by fusing the
ends together, or otherwise, so as to render the spiral virtually continuous. The
upper hemisphere of the spiral envelope has an axial opening of a size to permit
the passage of the bulb a¹, and the lower end of the spiral is adapted, as before,
to be centred upon the point of the bulb. The outer globe which is adapted
to closely embrace the spiral e so as to form the support for the latter, is made as
before in two parts el, e², which after being superposed upon the spiral care
united at the joint e between their meeting edges by means of a silicate, Canada
balsam, or other suitable cement, or by an equatorial band h of plastic glass.
The upper part el of the globe terminates as before in a neck ¹ cemented into
a metal ferrule g¹ and of an internal diameter sufficient to permit of its being
passed over the bulb a¹. The cap b₁ of the lamp is provided with a flange n
whose diameter is slightly greater than that of the ferrule g¹ so as to act as a stop
for the latter in order to prevent the lamp bulb being inserted too far within the
envelope. An annular rim o projects from the underside of the flange a and fits
within the ferrule g¹ so as to centre the envelope upon the lamp, the envelope
being secured in position and compelled to turn as one with the lamp when the
latter is inserted in, or removed from, its socket, by means of two or more
tongues (formed by slitting the rim o) which are bent outwards and upwards
through holes in the upper part of the ferrule g¹.
In the case of the arrangement last described, and illustrated in Figures 2
and 3, it will be seen that the glass spiral e and outer globe e¹, e², may be built up
5 apart from the lamp proper, so as to form an envelope complete in itself as shewn
in Figure 3 and capable of being applied to, or removed from, a lamp having a
cylindrical or other bulb whose greatest diameter does not materially exceed that

page_text: of the cap without the necessity of separating the envelope into its component
parts as in the first case.
It is to be understood that the invention is not limited to the precise details
of construction described in the foregoing specification and illustrated in the
drawings, as such details may be varied to suit the requirements of different
circumstances, without departing from the spirit of the invention.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:
(1) A light refracting and light diffusing screen for an electric lamp formed
of a spirally coiled glass rod and of a trunslucent globe or cover enveloping the
spiral rod so as to retain and protect it, substantially as specified.
(2) A light refracting and light diffusing screen for an electric lamp formed
of a spirally coiled glass rod and of a translucent globe or cover enveloping the
spiral rod so as to retain and protect it, the spiral rod and its enveloping globe
or cover being made in halves, each of which is of approximately hemispherical
form united for use as described.
(3) The combination with an electric lamp of a light refracting screen formed of
glass rod spirally coiled and adapted to enclose the lamp bulb and itself closely
enveloped by an outer globe or cover made in halves jointed together and affixed
to the cap of the lamp, substantially as specified.
(4) The combination with an electric incandescence lamp, of a light refracting
and diffusing medium consisting of a glass rod spirally wound so as to envelop
the bulb, and a globe or cover of translucent material wholly surrounding the
medium and halved together, the upper part of the globe or cover being provided
with means of attachment to the cap of the lamp and the two halves of the globe
or cover being secured to one another by a locking device substantially as and
for the purpose specified.
(5) The combination with an electric incandescence lamp of a light refracting
and diffusing envelope formed of a spirally wound glass rod and contained within
a translucent globe or outer cover made in halves permanently joined together,
the said globe or cover being provided with an opening giving passage to the
lamp bulb and with means whereby the globe or cover may be so connected to
the lamp that the two form a single structure, substantially as specified.
Dated this 20th day of December 1899.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.