Improvements in or connected with Alternating-current Arc-lamps.
Year: 1895

page_text: Date of Application. 16th Mar., 1895-Accepted, 4th May, 1895
COMPLETE SPECIFICATION.
Improvements in or connected with Alternating-current
Arc-lamps.
A communication by WILHELM MATHIESEN, of 4, Bahnhofstrasse, Leutzsch-
Leipzig, in the Empire of Germany, Manufacturer.
I, WILLIAM Phillips ThompSON F.C.S., M.1.M.E., of The Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster, 118 New Street, Birmingham in
the County of Warwick and 31 High Holborn in the County of Middlesex,
Civil 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 :-
In alternating-current arc-lamps, globes made of more or less semi-translucent
glass have hitherto been employed and a reflector placed either close over the arc
in the globe, or on the outside of the latter.
Both arrangements have the drawback that the rays of light radiated upward
from the arc, are firstly broken by a reflector, and secondly must pass through a
semi-translucent or light reducing glass so that a double loss of light results,
irrespective of which step succeeds the other.
The rays of light which pass upwards must necessarily be reflected if they are
to be utilized, but the necessity of passing them through semi-translucent glass is
avoided by the arrangement which forms the object of this invention.
In the accompanying drawings,
Figure 1 is a sectional elevation of an alternating-current arc-lamp with an
outside reflector ;
Figure 2 is a similar view of a modification without the outside reflector ;
Figure 3 a further modification with a different shaped globe.
In Figure 1 the alternating-current lamp a is provided with an outside reflector b,
and with a globe c of opaline or semi-translucent glass or the like, in this case having
a semi-spherical shape, open at the top.
5
For the purpose of protection against the weather, or, when used indoors, for
protection against fire, the semi-spherical globe c is covered with a part d of clear
glass. The rays of light radiating upwards can pass unimpededly through this
glass, and are then thrown downwards from the reflector b without suffering any
loss on their way through semi-translucent or light absorbing glass.
A modified form such as shown in Figure 2 in which the glass cover d is omitted
may in suitable cases be employed for indoor use. For indoor use, a white cover
may also be used as a reflector, and the reflector b shown in Figure 1 dispensed
with.
A third modification of this arrangement is the one shown in Figure 3 in which
the lamp is provided with an entire spherical globe of clear glass, within which a
small half globe f of semi-translucent glass is arranged. The effect in this case is
the same.
The light radiated downwards passes through the semi-translucent
glass, whilst that radiated upwards passes unimpededly through the clear glass and
is then thrown down by means of the reflector b.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent. I declare that what I claim is :-
1. In alternating-current arc-lamps the arrangement of a half globe of semi-
translucent or light-absorbing glass either open at the top, or covered by clear
glass, in combination with an outside reflector placed above the same, or for use in
indoor installations with a white cover for the purpose of utilizing the rays of light
radiated upwards without forcing them to pass through semi-translucent glass,
substantially as described.
2. In alternating-current arc-lamps, the arrangement within a clear glass globe
of a small semi-globe of semi-translucent glass open at the top, together with an
outside reflector placed above the clear glass globe, substantially as and for the
purpose set forth."
Dated this 15th day of March 1805
WM. P. THOMPSON & Co.,
Agents.