Year: 1886

page_text: Date of Application, 22nd Sept., 1886
Complete Left, 21st July, 1887
Complete Accepted, 22nd Dec., 1887
I, ALBANY FEATHERSTONHAUGH, of the Junior United Service Club Charles Street
London in the county of Middlesex Major in the Royal Engineers do hereby declare
the nature of this invention to be as follows:-
My Invention has for its object to obtain from a single incandescent lamp, more
light with the same electric current than two or more lamps of the kind now generally
used will give. To do this I place in the glass globe of my single lamp two or more
filaments or two or more wires as the case may be side by side and close together so
that the heat from each reinforces that from the other and there is less loss by
radiation. For these reasons more light is produced by each by a given strength of
current in each, and a lamp having two filaments side by side in the same glass globe
will give more light than two lamps arranged in parallel order of which each has a
single filament, the other circumstances being the same.
In putting the filaments or wires side by side I place them as close to each other as
is necessary to produce the heat saving effect described above and in order to do this
conveniently and effectively I make the system of filaments or wires of any shape that
may be desirable and I arrange them in the glass globe with such modifications in the
shape and size of the latter as may enable me fully to carry out my improvement.
Dated this Twenty first day of September 1886.

page_text: Improvements in Electric Incandescent Lamps.
I, ALBANY FEATHERSTONHAUGH, of the Junior United Service Club, Charles Street,
London, in the County of Middlesex, Lieutenant-Colonel in the Royal Engineers do
bereby 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:-
My invention consists in placing in an electric incandescent lamp two or more
filaments or two or more wires as the case may be side by side and close together so
that each filament is partly shielded by the other or others and a certain portion of
the heat generated by the electric current is prevented from escaping away by
radiation. The effect of this is to increase the intensity of the light produced, for
although a certain portion of the light from each filament is lost from being interrupted
by the other filament, or filaments, yet the light lost in this way is simply proportional
to the heat saved by the same cause, whereas the light which does go forth to the
surrounding space is proportional to the third or fourth power of the whole heat. The
increase of the whole heat by my invention increases therefore the useful light
produced.
In carrying out my invention I take two or more carbonized filaments and place
them in a glass globe side by side and close together, arranging them in multiple arc
and so that the current passes in the same direction along them all. Figures 1 and 2
in the accompanying drawing shew two arrangements of filaments a a in this way.
Again I take two or more filaments and twist or plait them together before
carbonization, I then carbonize them and use the compound filament so made.
Figure 3 shows this arrangement. I again take two or more carbonized filaments
and arrange them in a lamp in the way shewn in figure 4 where they are all in one
plane, or in the way shewn in figure 5 where they form a drum shaped system being
fixed in a circle of which figure 6 is a plan.
Again I twist or plait the filaments together in twos or threes or in greater numbers
and after carbonization arrange the compound filaments so formed in the ways shewn
in figures 4, 5 and 6.
Besides the arrangements mentioned above, I may adopt any others that may be
desirable subject to the condition that the filaments or wires should be close together.
I arrange wires in the same ways and by the term wires I mean metallic wires
whether they are coated or incorporated with other materials or not.
In saying that I put the filaments or wires side by side and close together I do not
mean that each filament is close to all the others but I mean that each filament is close
to at least one other. The general details of the glass work and of the connections of
the leads or terminals with the filaments or wires are analogous to those now in use,
and, when necessary, flexible leads or springs are used to allow for expansion and
contraction of the filaments.

page_text: I am aware that patents have before this been granted for lamps with multiple
carbons or filaments but in all such cases the carbons or filaments have been kept
apart from each other as far as the space in the lamp would allow or as far as other
necessary conditions would permit so that they might not interrupt each other's light.
I do the contrary for I place the filaments close together and even touching each
other and find an advantage in doing so.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I declare that what I claim is :
In electric incandescent lamps placing, in the same lamp, two or more filaments or
two or more wires as the case may be side by side and close together, substantially
as described, so as to increase the light by the saving in heat so effected.
Dated this Twentieth day of July 1887.
ALBANY FEATHERSTONHAUGH.