Improvements in Arc Lamps, specially applicable for Lantern Purposes.
Year: 1896

page_text: Date of Application, 12th June, 1896
Complete Specification Left, 10th Mar., 1897-Accepted, 10th Apr., 1897
PROVISIONAL SPECIFICATION.
Improvements in Arc Lamps, specially applicable for Lantern
Purposes.
I FREDERICK WOODWARD BRANSON of Commercial Street Leeds in the
County of York Pharmaceutical Chemist and Scientific Instrument Manufacturer
do hereby declare the nature of this invention to be as follows:-
This invention relates to are lamps more especially to such as are employed for
lantern purposes, and to that type in which the carbons are carried at the ends of
two hinged levers; and the object of this invention is chiefly the construction of
such lamps in such a manner, that the position of the arc remains practically
constant during the necessary feed of the carbons together as they burn away;
which is not the case with ordinary straight carbons attached to the ends of
pivotted levers; whilst the additional advantage is obtained, that the inclination of
the carbons always remains the same as that first given to them, which may suitably
be such as to throw the fullest amount of light towards the condenser.
The latter object I attain by employing in place of each pivotted lever, a pair of
levers of equal length pivotted on separate fixed centres, and connect the outer ends
of these levers by means of a pin jointed link, the length of which between the
centres is equal to the distance between the aforesaid fixed centres, thus constituting
a parallel motion. The carbon holder is attached to the just mentioned link by
means of a pin joint and a tightening nut, so that if found advisable the inclination
of the carbon can be adjusted. It will be evident that the parallel motion
arrangement of the arm retains the carbon in the same inclination (to which it may
have been adjusted,) during the feeding movement of the arms.
For the sake of distinction the upper and lower parallel motion arrangements of
levers will be hereafter designated, the upper arm and lower arm respectively.
The upper and lower arms are connected together by connecting the lower lever of
the upper arm and the upper lever of the lower arm by means of a connecting link,
attached at its ends to points of said levers on opposite sides of their respective
centres; and they are moved together or apart, and mounted in a swivelling block
as described in the Specification of my invention dated 1st November 1895
No. 20626.
To preserve the arc or the ends of the carbons always in the same position (as
the carbons are fed together to compensate for their burning away), the connection
of the just above mentioned link is made to the levers in such a manner, that the
long levers of both parallel motions are simultaneously at right angles to the lines
joining their fixed centres or pivots respectively. If this condition is fulfilled, the
carbons move simultaneously inwards and outwards towards and from the lines
joining their fixed centres respectively. In order that this movement shall be
practically negligible during the working of the lamp I further arrange that the
position of the long levers when they are simultaneously at right angles to the lines
joining their respective fixed centres or pivots bisects the arc through which the
levers move during the feed of the carbons.
In order to provide a lateral adjustment of one or both of the carbon holders, the
pin of the pin joint is made to pass through a slot in the horizontal stem of the
carbon holder, and a spring is interposed between the end link of the parallel

page_text: motion (or the stem) and the previously mentioned tightening nut. A slight
vertical ridge or knife edge is formed on one side near the forward edge of the end
link, against which the side of the stem bears or rests, so that the stem can be
tilted laterally about such ridge or knife edge as a fulcrum. An adjusting screw
bearing against the inner end of the carbon holder stem serves to tilt the stem, and
move the carbon laterally. The aforesaid spring serves to keep the end of the
stem pressed sufficiently tightly against the adjusting screw.
A longitudinal adjustment of the carbon may be effected by means of an
adjusting screw traversing the slot hole of the stem along over the before
mentioned pin.
In place of the parallel motion arranged as above described, the movement of the
carbons so as to keep the position of the are practically constant may also though
less conveniently be obtained by using an imperfect parallel motion i.e. one in
which the levers and end links of the same are respectively of unequal lengths,
choosing such lengths of levers and links and positions for the fixed centres as shall
retain a constant position for the arc, without necessarily retaining à constant
inclination of the carbons.
Dated this 11th dow of Time 1000
J. CLARK JEFFERSON,
30 Park Row, Leeds, Agent for Applicant.
Improvements in Arc Lamps, specially applicable for Lantern
Purposes.
I FREDERICK WOODWARD BRANSON of Commercial Street Leeds in the
County of York Pharmaceutical Chemist and Scientific Instrument Manufacturer
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 relates to are lamps more especially to such as are employed for
lantern purposes and to that type in which the carbons are carried at the ends of
two hinged lovers and the object of this invention is chiefly the construction of
such lamps in such a manner that the position of the arc remains practically
constant during the necessary feed of the carbons together as they burn away;
which is not the case with ordinary straight carbons attached to the end of
pivotted levers whilst the additional advantage is obtained that the inclination of
the carbons always remains the same as that first given to them which may suitably
be such as to throw the fullest amount of light towards the condenser.
The latter object I attain by employing in place of each pivotted lever a pair of
levers of equal length, pivotted on separate fixed centres, and connect the outer ends
of these levers by means of a pin jointed link, the length of which between the
centres is equal to the distance between the aforesaid fixed centres, thus constituting
a parallel motion. The carbon holder is attached to the just mentioned link by
means of a pin joint and a tightening nut, so that if found advisable the inclination
of the carbon can be adjusted. It will be evident that the parallel motion
arrangement of the arm retains the carbon in the same inclination, (to which it may
have been adjusted), during the feeding movement of the arms.
For the sake of distinction the upper and lower parallel motion arrangements of
levers will be hereafter designated the upper arm and lower arm respectively.
The upper and lower arms are connected together, by connecting the lower lever of
the upper arm and the upper lever of the lower arm by means of a connecting

page_text: link, attached at its ends to points of said levers on opposite sides of their respective
centres; and they are moved together or apart and mounted in a swivelling block
as described in the Specification of my invention dated 1st November 1895
No. 20626.
To preserve the arc or the ends of the carbons always in the same position as
the carbons are fed together, to compensate for their burning away, the connection
of the just above mentioned link is made to the levers in such a manner, that the
long levers of both parallel motions are simultaneously at right angles to the lines
joining their fixed centres or pivots respectively. If this condition is fulfilled, the
carbons move simultaneously inwards and outwards towards and from the lines joining
their fixed centres respectively. In order that this movement shall be practically
negligible during the working of the lamp, I further arrange that the position of
the long levers when they are simultaneously at right angles to the lines joining
their respective fixed centres or pivots, bisects the arc through which the levers
move during the feed of the carbons.
In order to provide a lateral adjustment of one or both of the carbon holders,
the pin of the pin joint is made to pass through a slot in the horizontal stem of the
carbon holder, and a spring is interposed between the end link of the parallel
motion or the stem and the before mentioned tightening nut. A slight vertical
ridge or knife edge is formed on one side near the forward edge of the end link,
against which the side of the stem bears or rests; so that the stem can be tilted
laterally about such ridge or knife edge as a fulcrum. An adjusting screw,
bearing against the inner end of the carbon holder stem, serves to tilt the stem
and move the carbon laterally. The aforesaid spring serves to keep the end of
the stem pressed sufficiently tightly against the adjusting screw.
A longitudinal adjustment of the carbon may be effected by means of an
adjusting screw traversing the slot hole of the stem, along over the before
mentioned pin.
In place of the parallel motion arrangement as above described, the movement
of the carbons so as to keep the position of the arc practically constant may also
though less conveniently be obtained by using an imperfect parallel motion,
i.e. one in which the levers and links of the same are respectively of unequal
lengths; choosing such lengths of levers and links and positions for the fixed
centres, as shall retain a constant or nearly constant position for the arc, without
necessarily retaining a constant inclination of the carbons.
And in order that my invention and the manner in which the same is to be
performed may be more readily understood, I have annexed hereto the accom-
panying drawing, in which
Fig. 1 is a side elevation of an arc lamp constructed in accordance with my
invention; and in which the swinging bracket e is shewn partly in section in order
to expose the corresponding ends of the levers.
9
Fig. 2 is a plan of the outer end of the lower arm.
a is a bed plate, to which a base piece b is hinged at c. d is a vertical bracket
secured to the base piece b; and e is a swinging bracket mounted on tihe vertical
bracket by means of a stud or pin f, about which the swinging bracket e can be
tilted, as described in the Specification of Letters Patent No. 20626 of 1895.
and glare a pair of levers hinged in the (fixed) centres i and , formed in the
sides of the swinging bracket e; and which are connected by pin joints at their
outer ends by means of a link k the length of which is equal to the distance
between the centres i and . This parallel motion arrangement constitutes the
upper arm. j and are a pair of levers hinged in the (fixed) centres o and o¹
formed in the sides of the swinging bracket e, and which are connected by pin
joints at their outer ends by means of a link 1, whose length is equal to the
distance between the centres o and o'. This parallel motion arrangement constitutes
the lower arm.
The lower lever g of the upper arm is bent beyond the centre i nearly at right
angles, and this bent portion is kept pressed against the end of the screw.n by

page_text: means of the spring p, attached at one end to the lever g and at the opposite end
to some portion of the swinging bracket e.
The lower lever g of the upper arm and the upper lever j of the lower arm are
connected together from opposite sides of the centres i and o by means of the link m,
the attachment of the link being by means of pin joints, so that when the bent
portion of the lever g is moved or allowed to move by screwing forward or back-
ward the screw n, the upper and lower arms simultaneously move apart or approach
each other.'
The carbon holder q of the upper arm is formed in one arm of a hinged bell
crank lever, the other arm of the bell crank lever carrying a swivelling bearing r
for the end of the screw rod s. The bell crank lever qr is hinged to the link k
by means of the stud or pin t. The screwed portion of the rod s is passed through
a nut v secured to the lever g'. By these means on rotating the screw rod s, the
top carbon holder can be tilted as required about the stud t.
wo is the bottom carbon holder, the stem or shank of which is provided with a
slot hole, through which the pin or study securing it to the end of the arm
(i.e. link ) passes. The shank is held against the link by the pressure of the
spring z. This device serves to allow the carbon holder to be adjusted in the
direction of the arm, and also tilted about the stud y.
In order to provide a lateral adjustment of the carbon holder, the outer edge
of the link on the side next the stem of the carbon holder is provided with a
slight ridge or knife edge 1, whilst an adjusting screw 2 passing through a tapped
hole near the inner side of the link serves to tilt the carbon holder about the
knife edge 1, i.e. laterally.
The arcs moved through by the levers g and j are indicated by dotted lines, the
levers being drawn in mid position. For the reasons previously mentioned,
the lever g. when in the position shewn (i.e. mid-position), is preferably at right
angles to the line joining the centres and ; and likewise the lever j at right
angles. to. the line joining the centres o and o¹; and the connection by the link m is
preferably so made, that the levers g and j are simultaneously in their respective
mid-positions.
The motion of the carbon holders may be made practically straight by attaching
the joints and o¹ of the levers gl and j to a radius bar hinged to pivots (for
example K and N) attached to lugs projecting from the swing bracket e, the ends i
and of being guided in slot holes."
§ Other means of operating the feed may be employed than that described and
shewn.
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 are lamps the combination of two pairs of levers, in which all the levers
are pivotted towards the one end in fixed centres and the opposite ends connected
in pairs by means of pin jointed links, the lengths of the levers and of the
connecting links being preferably such that each pair of levers and links constitutes
a parallel motion, carbon holders attached to said links, and means for operating
said parallel motions (arms) so that they simultaneously approach each other and
simultaneously move away from each other.
2. The modification of Claim 1, obtained by hinging the inner end of one of
the levers of each pair to a radius bar substantially as set forth.
3. In arc lamps the combination of parallel or approximately parallel motion
arms with means for operating the same substantially as set forth and illustrated.
4. In arc lamps having parallel or approximately parallel motion arms the bell
crank arrangement of the carbon holder hinged or pivotted to the end link of the
arm and operated by a screw rod, the screwed portion passing through a nut
attached to one of the long levers of the parallel motion arms, substantially as and
for the purpose herein set forth.

page_text: 5. In arc lamps the means for obtaining a lateral adjustment of the carbon
holders consisting of a knife edge or ridge fulcrum at the end of the arm carrying
the carbon holder and adjusting screw for tilting the carbon holder about said
fulcrum and spring for keeping the stem of the carbon holder pressed against said
fulcrum substantially as set forth.
6. In arc lamps the combination of the means for adjusting the carbon_holder
longitudinally and laterally substantially as set forth and illustrated in Figs. I
and 2.
7. The arrangement and combination in arc lamps of parallel or approximately
parallel motion arms and means for tilting and adjusting longitudinally and
laterally one or both the carbon holders substantially as set forth and illustrated.
8. My improved arc lamp substantially as herein set forth and illustrated in the
accompanying drawings.
Dated this 9th day of March 1807
J. CLARK JEFFERSON,
30 Park Row, Leeds, Agent for Applicant.