IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Herbert John Haddan at the Office of
the Commissioners of Patents on the 4th October 1881. A communication
from abroad by Léon Somzeé of Brussels, Belgium.
HERBERT JOHN HADDAN, of Kensington, Middlesex. "IMPROVEMENTS IN
ELECTRIC LAMPS." A communication from abroad by Léon Somzeé, of Brussels,
Belgium.
The principle of this Invention consists chiefly in constructing electric lamps,
made luminous by incandescence, as well as by the voltaic arc, by means of
continuous or alternating currents which produce the incandescence of a thin rod
(preferably of carbon) and a voltaic arc at the circumference of a rod of refractory
material, which may be fixed or movable on the second electrode of largo
section.
If the said refractory material is movable, its fusibility, volatilization, and dis-
aggregation are independent of the wear of the large carbon. If it is fixed it may
be partly or wholly encased in the large electrode or form a lining to the latter, in
which case it is arranged to disappear in proportion to the combustion of the large
carbon. In the lamp with movable refractory material one or more carbon rods
tending to approach a large block are arrested at a given distance from this block
by a rod of refractory material which rests on the large carbon.
In order to preserve the position of the luminous point during the combustion
of the carbons the large carbon as well as the thin carbon rod and the refractory
material are caused to move towards their mutual points of contact.
In the lamps with fixed refractory material one or more thin carbon rods are
made to abut against a prism of refractory material encased in the large carbon.
The section of the carbon rod is similar to that of the prism but a little smaller,
and the motion necessary for replacing the material worn away is restricted to the
thin carbon electrode. The voltaic arc is formed between the circumference of the
thin carbon rod and the edge of the refractory material; it can be increased or
decreased on any side of the carbon rod by increasing on that side the distance
between the edge of the carbon rod and that of the refractory material, thereby
decreasing the length of the arc on the opposite side. The most practical arrange-
ment of a lamp with fixed refractory material consists in holding the large (positive)

page_text: carbon between the sides of an iron frame to which the binding post for the
positive wire of the circuit is secured, while the negative carbons form two
symmetric arcs of a circle and are attached with their upper ends to two arms
which turn on a common centre.
The own weight of the carbons and of the arms causes the lower ends of the
'carbons to rest on the exposed right and left side of the refractory material which
is embedded in the large carbon. The electric current enters through the large
carbon, passes through the (incandescent) refractory material to the incandescent
lower ends of the thin (negative) carbon rods and through their common pivot to
the second binding post.
If the refractory material is attached to the large electrode the motion in the
lamp is restricted to the thin carbon rod, which may move in the direction of its
length and also perpendicularly thereto, preferably under the influence of gravity.
The refractory material may form an internal lining to a hollow carbon rod, while
a second (solid) carbon rod forms the negative electrode and descends by its own
weight in proportion to its combustion; or the positive carbon may be a hollow
truncated cone abutting with its thin end against a base of very refractory material
perforated in the centre and not intended to melt away, the arc being reflected by
the surfaces of the refractory material and of the negative carbon upon which it
rests. The refractory material and the carbon to which it is attached may form
two symmetrically arranged circular curves, ono curve having the refractory lining
inside while the other has it outside.
The refractory material should be thicker than the carbon rod to which it is
attached, and the width of the positive carbon should be less than that of the
negative electrode.
Or the electrodes may be straight and form an angle at their poles or lower ends
while their upper ends are attached to two rods converging upwards and provided
with weights, the contact of the poles being prevented by a rod of fusible material
about 1 to 3mm thick and of variable width, said rod being placed in the centre
between the carbons and attached at the top to a suspension rod. In proportion as
the carbon points burn away their point of intersection rises and follows the inter-
posed refractory material, under the influence of gravity, the refractory material
being completely independent of the two electrodes.
The lamp may be composed of a metallic frame which carries at its base the
large carbon block forming two symmetrically inclined planes, while two symme-
trically inclined carbon holders are so pivoted to the upper part of the frame that
the weight of the carbon holders with their carbons causes the latter to constantly
touch the outer ends of the inclined planes while the refractory material and large
carbon are wearing away. The refractory material may be sunk into grooves
of the large carbon electrode or placed upon the latter so as to form the larger
portion or the whole of the inclined planes.
If the electrodes form two symmetrical circular curves they may be attached
with their upper ends to radial arms, turning on a common centre, through which
the current enters.
Instead of arcs of a circle the two electrodes may form two symmetrically curved
spirals in order to use very long carbons in a small lamp. The carbon points tend
to approach each other by gravity, but are prevented from actual contact by the
interposition of a blade of refractory material. The latter is a fixed thin
rod destined to be consumed with the carbons and placed in their axis of
symmetry.