Year: 1888

page_text: I, JOHN HENRY HOLMIS of Portland Road Newcastle-on-Tyne in the County of
Northumberland, Electrical 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
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This invention has for object improvements in arc lamps, and relates to means for
feeding the carbon
I will describe the invention as applied to a lamp in which the carbons are sot
vertically the one over the other, and in which the upper carbon only receives the
feed motion It may however be applied to focussing lamps, and to lamps in which
the carbons are inclined
The upper moveable carbon is supported by a rod which is by preference cylindrical
This rod is carried in a fixed bearing through which it can slide It is however
prevented from dropping through the bearing under the influence of gravity by a
brake or slipper block, which is held against it upon one side by a bent flat spring
attached to a rigid bir This bar is pivotted or hinged to the upper part of the
bearing or some other suitable support in such a manner as to allow of it having
imparted to it when the feed is to take place a reciprocating swinging or vibrating
movement by an electro-magnet in a manner described bolow
To maintain the pressure of the spring upon the rod and to keep the bar in a position
approximately parallel to the rod a stop rigidly connected to the bearing may be
provided for the lower end of the bar to press against
Or, as I prefer to arrange it, a spring may be used exerting a pressure between a
rigid part of the lamp and the bar, so as to keep the latter in the required position
When the bar is moved the bent spring suffers a change of form
When the lower end of the bar moves towards the bearing the spring becomes
straightened, and its effective length is thereby increased and the pressure it exerts
upon the brake block is augmented, when the bir recedes the spring bends to
sharper curvature under its natural elasticity and its effective length is thereby
decreased and the pressure upon the brake block is lessened

page_text: The block acts as a friction pawl alternately gripping the rod and driving it down-
wards and slipping idly back again The downward motion of the rod is assisted by
gravity and any tendency of the rod to move upwards with the pawl is also opposed
by the same force
The vibration necessary for actuating the carbon feeding device described above
may be very simply obtained in the same manner as in electric bells, and to this end
I employ an electro magnet or solenoid the wire on which may form shunt past
the arc
An iron armature forming put of or attached to the vibrating bar is drawn
forward when sufhoient current is passing through the magnet to overcome the
adjustable pull of an opposing spring
In combination with the electro-magnet and its armature there is a make and break
apparatus so arranged that as long as the current through the coils off the magnet is
strong enough to cause the pull of the latter to overcome the opposing pull of the
spring the bar is hept vibrating to and fro As long as the vibration continues the
upper carbon is pushed slowly downwards so as to decrease the length of arc and
this goes on until, owing to the difference of potential between the carbons being
lessened, the shunt current is no longer powerful enough to cause the magnet to
attract its armature and the motion ceases
As the carbons are consumed the arc increases in length the difference of potential
becomes greater and the armature is again attracted by its magnet, thus feeding the
carbons together is required
It is not necessary that the electro-magnet described should have its circuit arranged
as a shunt to the arc, as it can be made to operate in a similar manner to that described
when it forms part of the main circuit and the make and break apparatus is a shunt to
its coils When thus arranged a decrease in the main current owing to the length
and the resistance of the arc increasing allows the armature to recede from the
magnet and to break the shunt circuit round it, the current in the magnet then
increases and the armature vibrates to and fro causing the feeding device to bring
the carbons nearer together
In the annexed sheet of drawings there is shown so much of an arc lamp as is
necessary to a clear understanding of my invention
Fig is an elevation with the cover removed and part of the electro magnet
removed for the sake of clearness
Fig 2 is an elevation at right angles to Fig 1 with the cover in section, but with
the lower part of the lamp shown
Fig 3 is a plan
The upper carbon A is carried by a rod B which slides in a bearing formed by a
central pillar C Through a hole in the pillar there boars against the rod a slipper
block D which has a bent spring pressing against its back with sufficient force to
prevent the rod B shipping down between the block D and the opposite side of the
hearing The point of the spring takes into a nick or cavity on the back of the slipper
block or it may be pivotted thereto
The spring is connected to a swinging or vibrating bar G which is hinged or
votted at its upper end to the pillar C This bar carries an armature H situated in
front of an electro magnet E E This armature is subject when the lamp is in action,
to the attraction of the magnet on the one side and to the force of the spring
F
acting in the opposite direction The bar also carries a contact piece 1 which makes
contact with the screw J
'
An adjustable spiral spring K is arranged to act upon the bar G in the opposite
direction to the force with which the spring F presses upon it and this tends to main-
tain the bar G approximately parallel to the rod B
The electro-magnet E E is arranged as a shunt to the arc The current proceeds
from the positive terminal of the battery to the contact screw J, thence through the
contact piece I and through the coils of the magnet to the negative terminal
The operation of the lamp is as follows
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As the carbons waste, the length of the arc increases, and consequently there is an
augmentation of the current in the magnet E E When the length of the arc exceeds

page_text: the amount for which the lamp is adjusted, the armature H is moved towards the poles
of the magnet carrying with it the bar G By this motion the spring F is straightened
(or approximately so) and its end pressed more strongly on the shipper block D which
moves downwards carrying the rod B with it But the movement of the bar G breaks
the circuit and consequently the magnet loses its power The bar then swings back
under the influence of the spring F which spring bends under the action of its own
elasticity and at the same time its pressure upon the block D decreases and the block
moves upwards The restraining action of gravity upon the rod B prevents it moving
upwards with the block D If the arc is by this feed action reduced to the required
length the motion ceases, but if not the vibration of the bar G continues until this
result is attained
The lower electrode is carried upon the armature of an electro magnet the
coils of which are included in the main circuit, so that as soon as the current is
started the armature is drawn down in opposition to the force of a spring and the are
18 thus struck
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim 19
In an arc lamp,
1st A feeding device comprising a slipper block or friction pawl and curved
spring the arrangement being such that the spring can be caused to become less
curved and more curved alternately thereby moving the shinner block or nawl forward