Improvements in Electric Arc Lamps of the Enclosed Type.
Year: 1898

page_text: Date of Application, 20th July, 1898
Complete Specification Left, 20th May, 1899-Accepted, 20th Oct., 1899
Date of Application, 20th July, 1898
Complete Specification Left, 20th May, 1899-Accepted, 20th Oct., 1899
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps of the Enclosed Type.
LOUIS JOHN STEELE, Electrical Engineer, of 14, Clarendon Road, Holland Park,
W., London, in the County of Middlesex, do hereby declare the nature of this
invention to be as follows:-
In arc lamps known as the enclosed type, that is, using a more or less air
tight chamber in which the combustion of the arc light carbons takes place, the
life of these carbons is increased by raising the temperature of the surrounding
gases; this also has the effect of diminishing the deposit of particles on the inner
surface of the said chamber. In order to still further lengthen the life of the car-
bons, to increase the steadiness of the light, and to reduce the deposit of particles
on the surface of the chamber to a minimum, I employ a chamber or chambers
so constructed that the chamber containing the gases, in which the arc takes place,
is surrounded by a vacuum.
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps of the Enclosed Type.
I, LOUIS JOHN STEELE, Electrical Engineer, of 14, Clarendon Road, Holland
Park, in the City of London, 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 electric are lamps of the enclosed type or, in other
words, to those lamps in which the electric are burns in a more or less air-tight
chamber, hereinafter referred to as the arc chamber.
In such lamps the life of the carbons is increased, and the deposition of carbon
and other particles upon the inner surface of the arc chamber is diminished, by
the fact that the temperature of the surrounding gases in the said chamber is
raised.
This invention is characterised by certain improvements which have for their
object firstly, to still further lengthen the life of the carbons, secondly, to increase
the steadiness of the light, and thirdly to still further diminish the deposition
of particles upon the inner surface of the arc chamber. The said improvements
consist in substance in the employment of a vacuum chamber or a number of
vacuum chambers, of any desired shape, form and dimensions, to surround or
enclose the arc chamber as aforesaid and ensure its isolation from the surround-
ing air, and put between it and the said air a non-conductor of heat which will
not interfere with the light giving effect of the arc.
A method of carrying this invention into effect is shown in the accompanying
sheet of drawings in Figs. 1, 2, and 3, a portion of an arc lamp of the enclosed

page_text: type being shown with the invention applied in Fig. 1. Fig. 2 is a horizontal
section through the inner globe Fig. 1, and Fig. 3 is the inner globe separate,
with an additional fitting. In the arrangement shown in the drawings a single
vacuum chamber c surrounds the arc chamber d, the said vacuum chamber being
formed by a double wall or jacketted construction of the inner glass globe, a,
which is made more or less air-tight by end fittings a², a³, and into which the
carbons g, m, extend. The vacuum in the chamber c is obtained at the time of
the globe's formation or subsequent thereto, preferably by a mercury pump in
the same manner as the bulb of a glow lamp, and its presence so insolates the
exterior air from the body walls of the arc chamber as to prevent any radiation
of heat from the arc chamber in that direction, and stops all conductivity between
the heated inert gases in the arc chamber and the cooler gases without, the said
vacuum being practically an interposed heat resistance.
It will therefore be obvious that by this invention the temperature of the gases
in the arc chamber can be considerably increased and kept constant, and also
that the exterior surface of the inner globe is quite cool, whilst nothing is
present to interfere with the light giving powers of the arc.
The vacuum chamber c may be divided and may be of any shape and size so
as to extend top and bottom of the globe, and may be suitably strengthened
against its exterior walls becoming fractured.
In Fig. 3 a metal ferrule or cap is fitted to the top end of the combined
globe and vacuum chamber to compensate by its power of conduction for the
differences between the temperature of the top portions of the walls of the arc
chamber and those of the vacuum chamber.
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:
First. In arc lamps-of-the enclosed type the provision of a vacuum chamber
or vacuum chambers constructed so as to surround or partly surround the arc
chamber wherein the arc burns and which is so formed as to present no obstacle
to the light giving properties of the said are for the purposes substantially as
described.
Second. An arc lamp of the enclosed type characterised by a vacuum chamber
or a number of such formed in one with the inner globe or arc chamber so as
to surround or partly surround the walls of the said arc chamber and which is
either formed in one with the said globe or by a secondary wall or jacket made
air-tight thereto substantially as described and set forth.
Third. In arc lamps of the enclosed type the provision of a vacuum chamber
to surround the outer walls of the inner globe which forms the arc chamber
the said vacuum chamber being constructed and arranged in the particular
manner set forth in Figs. 1 and 2 and Fig. 3.
Dato This
TMAYAY
13344
W. P. THOMPSON & Co.,
11, Burlington Chambers, New Street, Birmingham,
Also of Liverpool, London and Manchester,
Patent Agents for the Applicant.