Improvements in the Form of Carbons used in Certain Electric Arc Lamps.
Year: 1891

page_text: Date of Application, 25th Mar., 1891
Complete Specification Left, 23rd Jan., 1892-Accepted, 19th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Form of Carbons used in Certain Electric Arc
Lamps.
We THOMAS PHILIP CHRISTOPHER CRAMPTON of 10 Cursitor Street
Chancery Lane in the County of Middlesex Electrician and ALBERT ESSINGER
of 19 Clifton Hill Saint Johns Wood in the same County Gentleman do hereby
declare the nature of this invention to be as follows:-
In the first place our invention relates to the bottom carbon of electric arc lamps
where this carbon is fed up from below by means of a weight or otherwise so as
to cause the carbon to constantly press against points formed of what is known as
platina-irridium or some other highly refractory material.
We so form the carbon as to prevent any chance of slipping such as may some-
times occur when plain smooth carbon rods are used. For this purpose we form the
carbon with a series of horizontal ridges and grooves alternately. The effect of
this is as follows :-
The platina-irridium points being set to just catch sufficiently on one of the ridges
as the carbon burns away this ridge will be gradually destroyed until at last it allows
the carbon to slip through until the platina-irridium points catch upon the next
ridge and so on. Thus if there be twenty ridges to the inch, the feed will be
twentieth of an inch at a time.
Instead of using a number of separate horizontal ridges we might form the carbon
throughout its length as a screw having the requisite number of teeth to the inch.
Or we might form the lower carbon with three or more rows (according to the
number of platina-irridium points used) of alternate depressions and projections
forming narrow racks down the carbon parallel to its length. The platina-irridium
points catching on the teeth of these racks will only allow the feed to proceed at the
rate of one tooth at a time.
In the next place our invention relates to an upper carbon suitable to be used in
certain lamps.
In certain lamps the upper carbon is held in a holder which has a rack formed
upon it into which works a toothed wheel which in conjunction with other mechanism
regulates the feed of the upper carbon. Now by our invention we can form this
rack in the upper carbon itself so as to dispense with the carbon holder the feed
being applied direct to the carbon.
Dated this 25th day of March 1891.
זומא-י
.
THOMAS F. C. CRAMPTON.
ALBERT ESSINGER.
COMPLETE SPECIFICATION.
Improvements in the Form of Carbons used in Certain Electrio Aro
Lamps.
We THOMAS PHILIP CHRISTOPHER CRAMPTON of 10 Cursitor Street
Chancery Lane in the County of Middlesex Electrician and ALBERT ESSINGER
of 19 Clifton Hill St. Johns Wood in the same County Gentleman 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 the first place our invention relates to the bottom carbon of electric arc lamps

page_text: where this carbon is fed up from below by means of a weight or otherwise so as to
cause the carbon to constantly press against points formed of what is known as
platina-irridium or some other highly refractory material.
Fig. 1. in the accompanying drawings shews the lower part of an electric arc
lamp in which the lower carbon is fed up in the manner described. The weight "A."
is attached to the fine chain "B." which passes over a pulley at "C." the other end
of this chain being attached to a short rod or pusher below the carbon rod in the
tube "D." The weight thus causes the carbon (the point of which is seen projecting
at "E.") to be constantly pressed up against the platina-irridium points F. F. in the
crown piece G. An enlarged view of this crown piece with the platina-irridium
points F. F. F. is shewn in Fig. 2.
We so form the carbon as to prevent any chance of slipping such as may sometimes
occur when plain smooth carbon rods are used. For this purpose we form the
carbon with a series of horizontal ridges and grooves alternately. The effect of this
is as follows:
The platina-irridium points, being set to just catch sufficiently on one of the ridges
as the carbon burns away this ridge will be gradually destroyed until at last it
allows the carbon to slip through until the platina-irridium points catch upon the
next ridge and so on. Thus if there be twenty ridges to the inch the feed will be
one twentieth of an inch at a time. A portion of a carbon rod so formed is shewn
in Fig. 3. We find that a very shallow groove will be required. For a carbon
rod of an inch diameter with three retaining points a groove of about 0 of an
inch deep will be sufficient.
Instead of using a number of separate horizontal ridges we might form the carbon
throughout its length as a screw having the requisite number of threads to the inch
as shewn in Fig. 4.
Or we might form the lower carbon with three or more rows (according to the
number of platina-irridium points used) of alternate depressions and projections
forming narrow racks down the carbon parallel to its length. The platina-
irridium points catching on the teeth of these racks will only allow the feed to
proceed at the rate of one tooth at a time. A portion of a carbon rod formed on
this principle is shewn in Fig. 5.
In Fig. 6. is shewn a modification of this form. Here a number of small circular
indentations are made down the carbon rod, the number of rows of these indenta-
tions corresponding to the number of platina-irridium points.
In the next place our invention relates to an upper carbon suitable to be used in
certain lamps.
In certain lamps the upper carbon is held in a holder which has a rack formed
upon it into which works a toothed wheel which in conjunction with other
mechanism regulates the feed of the upper carbon. Now by our invention we can
form this rack in the upper carbon itself so as to dispense with the carbon holder-
the feed being applied direct to the carbon.
In Fig. 7. we shew a very usual method of holding an upper carbon rod of an arc
lamp as at present made. H is the carbon rod. I is a metal rod with a socket K
at the end. The end of the carbon rod H is gripped in this socket. The rod I has
a toothed rack formed down one side and into this rack gears the small pinion L.
Motion is given to this pinion by clockwork or by mechanism actuated by the
current so that a slow downward feed is imparted to the carbon rod as it burns away.
Now this part of our invention consists in dispensing with the metal rod I. and
forming the rack on one side of the carbon rod itself so that the pinion L. gears
direct into the carbon rod as shewn in Fig. 8. In Fig. 9. is shewn a front view of
the rack formed down the side of the carbon.
We are aware that in some electric arc lamps ribbed or fluted carbons have been
used. The ribs or flutings to which we refer run parallel to or spirally with the
length of the carbon rod. They are not formed on the carbon with the view of
preventing and do not in fact prevent the slipping of the carbon which it is the
object of our invention to prevent.

page_text: Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:―
We wish it to be understood that we do not confine ourselves to the precise
details shewn in the drawings and described in the Specification but what we
claim is :-
1st. In electric arc lamps in which the lower carbon rod is fed up against retaining
points forming such lower carbon rods with ridges grooves threads projections
indentations or otherwise substantially as and for the purposes hereinbefore
described.
2nd. Forming the upper carbons of electric arc lamps with a rack in the side of
the carbon itself substantially as and for the purposes hereinbefore described.
Dated this 23rd day of January 1892.
THOMAS P. C. CRAMPTON.
ALBERT ESSINGER.