Improvements in Electric Aro Lamps.
Year: 1894

page_text: Date of Application, 11th June, 1894
Complete Specification Left, 5th Mar., 1895-Accepted, 24th May, 1895
Improvements in Electric Aro Lamps.
HENRY CAPEL LOFFT HOLDEN Major, Royal Artillery Royal Arsenal
Woolwich do hereby declare the nature of this invention to be as follows a
:―
For the purpose of my invention I construct an arc lamp as follows.
Both the positive and also the negative carbons are contained in holders which may
conveniently be in the form of metal tubes and through these metal tubes or holders the
carbons are pressed by the force of springs weights or gravity, at the same rate and at
the same time as each carbon is consumed in the arc. The carbons themselves are
prevented from being forced completely out of their holders by one or more screws
or an equivalent device or devices, which abutting against the consumable part of
the carbon, in proximity to the arc itself, regulate the forward feed of the
carbon rod in its holder automatically to suit the requirements of the current and
voltage.
. 31
The above mentioned holders are themselves supported by a frame having
Buitable adjustments for maintaining the arc in one place or with a fixed focal point,
as well as adjustments for separating the carbons and striking the arc in the first
instance and subsequently adjusting the length of the arc when burning.
These operations may be effected by an arbor passing through a sleeve on the
frame of the lamp, and having at one end a milled head or similar contrivance, by
means of which it can be made to revolve, and at the other a cam or disc mounted
excentrically, by the turning of which one of the carbon holders is made to approach
or recede from the other and the arc first formed and afterwards shortened
or lengthened as required.
When using the lamp for projection purposes in order to obtain the full useful
effect of the most intensely heated portion of the crater in the positive carbon as
light, the whole frame may be inclined to a greater or less extent.
Dated this Eleventh day of June 1894.
I, HENRY CAPEL LOFFT HOLDEN Major, Royal Artillery Royal Arsenal
Woolwich Kent, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
and by the following statement:-
.
in
My invention relates to improvements in are lamps and more particularly
to those used for the purposes of optical projection in lanterns or in projectors for
search lights, whereby these same lamps are rendered more convenient and simpler
in use and the light itself steadier than is the case with the greater number of lamps
in use at the present time whether they be regulated automatically or by hand or by
a combination of these methods.
4
In order that my invention may be fully understood, I shall now proceed more

page_text: particularly to describe the same, and for that purpose shall refer to the several
figures on the annexed sheet of drawings, the same letters of reference, indicating
corresponding parts in all the figures. Fig. 1. represents in side and front
elevation an arc lamp arranged according to my invention. A and B, which may
be of metal or other suitable material, are the two carbon holders containing the
positive and negative carbons respectively.
The carbon holders. A and B are each tubular in form and of such a size and
shape internally that the carbon rod can slide easily through them until its conical
end, where the arc is formed, is arrested by one or more adjustable pieces or points,
forming part of the carbon holder or. an extension thereof. The carbon rod is
continuously pressed up to these abutment pieces or points either by a spring, such
as a spiral one, which may conveniently be contained in the holder between the
end of the carbon rod and a cap on or a plug in the end of the holder itself,
or the carbon, if it be the upper one, may be pressed forward by a weight or even
by the action of gravity acting on the carbon rod itself. In this manner as the,
carbons burn away in use so they are respectively fed forward against the abutment
pieces and thereby preserve a constant length of arc and a fixed focal point.
These carbon holders are fixed to the two main portions of the lamp by
their respective clamps K. K so that they can be readily adjusted in position and
removed if necessary for replenishing with carbon.
The positive carbon holder A is clamped in position in the saddle of the metal.
frame C, this frame C in its turn being secured to the insulating base plate E.
The frame C carries the binding screw J. to which the positive conductor is secured.
The negative carbon holder is clamped in position on a saddle piece L. which is
capable of a to and fro movement on the two guides G G in a direction parallel to
the axis of the carbon holder B; the guides are fixed to the frame D which
is itself attached to the insulating base plate E..
The frame D carries the binding screw J to which the negative conductor. is
attached.
The frame D also carries an arbor which passes through a sleeve F in the upper
portion of the aforesaid frame, this arbor has at one end of it the milled head H',
preferably of insulating material, and at the other end a disc or wheel H. mounted
excentrically with respect to the axis of the arbor.
Attached to the saddle piece L. L. and bearing on the periphery of the wheel H.
is a small roller I.
The two spiral springs S. S. which are each attached at one end to the saddle and
at the other to the frame D serve to keep the wheel H. in close contact with the
roller 1; and consequently when the disc H is turned, the saddle L. I.. and with it
the carbon holder will be either raised or lowered as the case may be.
This arrangement is used for striking the arc in the first instance as well as for
regulating the length of the arc subsequently or it may be used only for regulating
the length of the are after the arc has been struck by an electro-magnetic device
such for instance as that shown in the form of lamp shown in Fig. 2.
The form of lamp shown in Fig. 2 is one specially suited for replacing the
limelight in optical lanterns as it can be clamped R to the tray rod Q which usually
carries the burner of the limelight apparatus.
In this form of lamp the adjustment of the lower carbon holder is effected by the
movement of the milled head H' which turns the arbor carrying the small roller H,
this latter rolls on an inclined surface I, causing the arbor itself to travel forward
or backward axially; the end of the arbor acts on the short arm of the lever D
carrying the carbon holder B, and this lever being pivotted at P. thus lowers or
raises the same carbon holder. In this instance the carbon holder B is shown with
an electro magnetic arrangement for striking the arc; this is of the usual description
in which the carbon is normally in contact the other carbon, the holder being
attached to the armature N. The armature N is attracted by the electro magnet M
whose coil is in the main or a shunt circuit, and thus causes the carbons to
separate and the arc to be struck on the passing of the electric current.

page_text: The carbon holders or the entire lamps themselves may be vertical, horizontal or
inclined so as to utilize the light from the arc in the most effective manner for the
particular purpose required.
Furthermore the positive carbon holder may be made movable or the negative
holder movable or both may be movable in the manner already described.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In electric arc lamps the combination or combinations of carbon holders whereby
the carbons are fed forward automatically as consumed, and the adjusting
mechanism or mechanisms whereby the distance between the said carbon holders or
between the points of the carbons can be regulated so as to give the length of are
required, substantially as and for the purposes herein before described.
Dated this Fourth day of March 1895.
H. C. L. HOLDEN, Major, R.A.