Year: 1895

page_text: Date of Application, 27th Feb., 1895-Accepted, 24th May, 1895
A communication by WILHELM AUGUST RASMUS MATHIESEN, of 4, Bahnhof-
strasse, Leutzsch, near Leipzig, in the Empire of Germany, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.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 :-
This invention has for its object an even diminution in the consumption of both
carbons in are lamps, whilst avoiding the drawbacks connected with other similar
devices.
In order to diminish the burning away of the carbons, it is necessary to limit the
quantity of air flowing to the arc, and to regulate accordingly the consumption of
oxygen in the arc. This is usually attempted by means of protective cases and
small globes enclosing the arc.
The protective cases or holders have (amongst others) the drawback that they
must assume an exactly determined position relatively to the point of the upper
carbon, a condition which it is difficult to fulfil. Further, such protective cases or
holders are unsuitable for alternating current lamps, as they impede the light
radiated upwards without reflecting it. The heat which destroys any enamel, the
white deposit, and the form of the holder or case itself, have all an impeding
effect.
The sinall glass bells or globes have the drawback of easily breaking under the
strong beat, and, in consequence of the white deposit which accumulates in large
quantity, become much more impervious to the rays of light. These drawbacks are
all avoided by the present invention.
The necessary diminution, mentioned at the commencement of this Specification,
of the quantity of air flowing to the are is bere obtained by a bell or globe which
encloses the bars of the lamp and is of suitable form and size, being so far rendered
air-tight that only a quantity of atmospheric air necessary for ensuring the steady
burning of the arc is admitted, whilst the exhausted air escapes together with the
gases of combustion at suitable places.
If an arc lamp arranged in this manner be connected up, the are first finds an
excessive supply of oxygen. The consumption of the latter is however much
greater than the supply, and consequently for instance in the case of a bell or globe
of 13 cubic decimetres of air capacity, with a current strength of 8 ampères, there
is produced within about half-an-hour an ultimate condition of the air in the globe,
in which it is poor in oxygen.
In the meantime the rate of combustion of the carbons has gradually decreased
to the desired degree.
If then such an arc lamp were only to be switched on for half-an-hour after long
intervals, the gain in the duration of combustion would only be small, but if such a
lamp larn from 2 to 3 hours a gain in the duration of combustion takes place to
double the amount. If the lamp be not shut off at all between times the gain
still greater.
15

page_text: If it be desired to obtain this great saving of carbons even in the case of lamps
which burn only for a short period at a time, it is only necessary by hand or auto-
matically to close or open, as the case may be, the air supply openings by means of
valves, slides or the like operated electro-magnetically, or by the action of heat.
It would appear questionable however whether the practical utility of such
automatically operated devices would equal the cost.
In the accompanying drawings :-
e
Figure 1 shows a round globe a, the upper flange of which is airtightly fitted
on to the disc or plate, preferably by means of asbestos, or other suitable washer
material. The outer air passes to the arc or through openings in the globe,
and escapes into the open air through the opening surrounding the upper carbon,
the protective cylinder being provided with holes through which the air may
pass. By this arrangement any heating of the regulating mechanism is prevented.
Figure shows a similar arrangement, but here the air passes through an
opening at the hottom. As however in the case of alternating currents, a portion
of the light is radiated upwards, and the small reflector shown in Figure 1 would
suffer extremely from the great heat, a plate or dish of clear glass is here
employed in order that the rays of light may fall on the reflector h placed outside
the globe.
In the case of greater strengths of current in order to avoid too great a heating
of the globe, the latter must he of larger dimensions.
Figure 3 shows one of these larger globes. Here a conical top is placed on the
half globe a, which conical top may be made of clear glass in order to allow the
rays of light which pass upwards to fall without hindrance on the reflector or it
may be made of opal glass to serve as a transparent reflector. It may of course
also be made of metal as a non-transparent reflector. In the two latter cases the
reflector may be dispensed with.
In the arrangement shown in Figure 3, the change of air takes place by means
of a single opening & arranged above the are light. If as in this case the inlet and
outlet of air takes place as high as possible above the are, an active interchange of
air takes place in the upper part of the globe, which allows the gases of combustion
to be carried off more quickly, and thereby essentially diminishes the coating of the
globe with deposit, whilst in proximity to the are the supply of air remains of the
necessary limited dimensions.
The fresh air flowing in is also strongly heated before it reaches the arc light,
which is only to a small extent the case, if the air enter from the side and still less
so if it enter from below.
As the consumption of oxygen is proportionate to the strength of current of the
are light, the admission of air must be capable of being regulated according to the
strength of current of the lamp.
The opening & in Figure 3 may be diminished in size or increased by adjusting a
slide p, in order to make such opening coincide with the strength of the necessary
change of air.
The regulation may be done in another manner by a small disc 7, as shown in
Figure 1, a plan view of which is also shown in Figure 4. This small disc which
may be of any suitable material, lies on the disc or plate c, and exactly encloses
the upper carbon without causing any impediment by friction as it is easily shifted
sideways.
The disc either serves for entirely closing the opening in the plate e, if the air be
required to escape at any other place, or it may be provided with air slots m iu
order to allow as much air to flow in or pass out through the same as may be
necessary.
The disc forms by its ready interchangeability a convenient means for regulating
the supply of air, by affording openings of equal size where carbons of various
diameters are employed, or openings of various sizes to suit different strengths of
current.
Figure 3 also shows an annular body n of metal or fire-resisting insulating

page_text: material such as porcelain, marble, steatite or the like which surrounds the upper
carbon at some little distance. This ring serves to catch a portion of the heat
arising from the arc, without limiting the supply of air. As soon as this ring is
sufficiently heated it serves to protect the space surrounding the arc and the points
of the carbons from cooling.
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 arc lamps, the usual arrangement of a globe of suitable form enclosing the
carbon holders or of a size corresponding to these, and attached to the case of the
lamp, said globe being however so far closed to the air that the outer air can only
have access to the interior of the globe or reach the current of air rising from the
carbons, to such an extent as is requisite for the steady burning of the arc, whilst
the exhausted air may escape through suitable openings, whereby the rate of
consumption of both carbons is reduced, substantially as described.
2. In the arrangement of arc lamps described in the foregoing claim, the
arrangement of the openings for the inlet and outlet of air (which may also be both
combined in one) above the arc, in the globe or in the globe holder, for the purpose
of carrying off the gases of combustion more quickly by means of the active change
of air taking place above the arc, whereby the deposit on the inside of the globe is
diminished and the arc supplied with air previously well heated, substantially as
described.
3. In the arrangements of arc lamps described in the foregoing claims, the
arrangement of slides, valves or interchangeable discs, tube pieces or the like,
adjustable by hand or automatically, for the purpose of regulating the size of the
air openings, substantially as described.
4. In the arrangements of are lamps, described in the foregoing claims, the
arrangement of a plate or disc of glass, shutting off airtightly the upper opening of
the globe for the purpose of allowing the light radiated upwards in the case of
alternating currents, to fall on a reflector arranged outside the globe, substantially
as described.
5. In the arrangements of arc lamps described in the foregoing claims, the
arrangement of a ring of metal or heat resisting insulating material surrounding at
some little distance the upper carbon, but not limiting the supply of air, with the
object of absorbing a portion of the heat produced by the arc, and thus protecting
the arc from cooling substantially as described.
6. In the arrangement of arc lamps described in Claims 1, 2 and 3, the arrange-
ment of a globe open at the top but covered by a closely fitting conical metal or
opal reflector, substantially as described.
7. In the arrangement of arc lamps described in Claims 1, 2, 3, 4 and 5, the
arrangement of a disc surrounding the upper carbon and wholly or partially tight-
fitting and provided with ventilating slots with the object of regulating the passage
of the air substantially as described.
Dated this 26th day of February 1895.
WM. P. THOMPSON & Co.,
Agents.