IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1882

page_text: LETTERS PATENT to Joseph Devonport Finney Andrews of Glasgow in the
County of Lanark North Britain for an invention of IMPROVEMENTS IN
ELECTRIC LAMPS
PROVISIONAL SPECIFICATION left by the said Joseph Devonport Finney
Andrews at the Office of the Commissioners of Patents on the 17th July
1882.
JOSEPH DEVONPORT FINNEY ANDREWS of Glasgow in the County of Lanark
North Britain IMPROVEMENTS IN ELECTRIC LAMPS"
"s
My invention relates to electric lamps of the arc kind in which a solenoid is
employed for regulation, the object which I have in view being to provide means
of compensating for the varying attraction exerted on the core when it takes
different positions within the solenoid. This attraction is greatest as the core
enters the solenoid and least when it is entirely within it. According to my.
invention the core is suspended by a chain passing over a pulley and carrying the
holder of one of the electrodes, the holder of the other electrode being attached to
the core.
Thus when the core is in its lowest position subject to the strongest
attraction the weight of the suspending chain is mostly on the same side with the
core opposing the attraction. As the core ascends into the solenoid the weight of
the chain diminishes on the one side of the pulley and increases on the other thus
compensating for the diminishing attraction of the solenoid.
According to a modified arrangement I employ two cores inside one solenoid
both suspended by a cord running over a pulley so that they balance each other.
To each core is attached one of the carbon holders. The two cores being within
one coil have their like poles presented in the same way and therefore tend to take
up a position such that their unlike poles approach each other in the middle of the
coil. As they move in opposite directions the attraction of their unlike poles
increases as the repulsion of their like poles diminishes.
According to another modification I fix a core in the upper part of the solenoid
and provide another core free to move vertically in the lower part of the solenoid.
In this case the attraction increases as the moveable core approaches the fixed core.
To compensate this I suspend a chain so that it is collected on a plate attached to
the moving core thus adding weight as it ascends. The chains employed may have
links differing in weight so as to compensate irregularities in the attraction of the
solenoids.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Josephi Devonport. Finney Andrews in the Great Seal Patent
Office on the 16th January 1883.
JOSEPH DEVONPORT FINNEY ANDREWS of Glasgow in the County of Lanark
North Britain. "IMPROVEMENTS IN ELECTRIC LAMPS
"
My invention relates to electric lamps of the arc kind in which a solenoid is
employed for regulation, the object which I have in view being to provide means
of compensating for the varying attraction exerted on the core when it takes
different positions within the solenoid. This attraction is greatest as the core
enters the solenoid and least when it is entirely within it.
According to my invention, the core is suspended by a chain passing over a
pulley and carrying the holder of one of the electrodes, the holder of the other
electrode being attached to the core. Thus when the core is in its lowest position
subject to the strongest attraction, the weight of the suspending chain is mostly
on the same side with the core opposing the attraction. As the core ascends into
the solenoid, the weight of the chain diminishes on the one side of the pulley and
increases on the other, thus compensating for the diminishing attraction of the
solenoid.
According to a modified arrangement, I employ two cores inside one solenoid,
both suspended by a cord running over a pulley so that they balance each other.
To each core is attached one of the carbon holders. The two cores being within
one coil, have their like poles presented in the same way and therefore tend to
take up a position such that their unlike poles approach each other in the middle
of the coil. As they move in opposite directions, the attraction of their unlike
poles increases as the repulsion of their like poles diminishes. According to
another modification, I fix a core in the upper part of the solenoid and provide
another core free to move vertically in the lower part of the solenoid. In this case
the attraction increases as the inoveable core approaches the fixed core.
To com-
pensate this, I suspend a chain, so that it is collected on a plate attached to the
moving core, thus adding weight as it ascends. The chains employed may have
links differing in weight so as to compensate irregularities in the attraction of the
solenoids.
DESCRIPTION OF THE DRAWINGS.
a is
Fig. 1 is a vertical section of one form of lamp according to my invention.
the solenoid having its iron core b attached at its lower end to the sliding holder
of the lower carbon and at its upper end to a chain c, which passes over the
pulley and is attached to the holder of the upper carbon. As the core b ascends,
the attractive force of the solenoid on it becomes lessened, but the chain becomes
lighter on the one side and heavier on the other, so as to compensate for the
diminution of attraction on the core. Fig. 2 shews a modified form in which two
cores band b² are fitted to move within the one solenoid a, these cores being at
their lower ends attached to the carbon holders and at their upper ends connected
by a cord c passing over a pulley d. It will be seen that the cores having
magnetism induced on them by the one solenoid have similar poles S at their
upper ends and also similar poles N at their lower ends. As the core b¹ descends
and 6ª ascends, the repulsion of the like poles becomes lessened, and the attraction
of the unlike poles becomes increased. In the form of lamp shewn by Fig. 3, the
core b of the solenoid a holds the upper carbon and is provided with a shelf e on
which rest a number of the links of chains c, the greater or less weight of these

page_text: links as the number supported is greater or less counteracting the greater or less
attractive power of the solenoid. A like result is obtained as shewn in Fig. 4, by
the use of a chain c attached at its one end to the fixed framing and at its other
end to the lower part of the core b. It will be seen that as bascends or descends
the weight of the part of the chain supported by it increases or diminishes.
Having thus described the nature of my invention and in what manner the same
is to be performed, I claim in respect of electric are lainps in which the attraction
of a solenoid on its core is employed for regulating the distance of the carbons ;-
First Compensating the increase and diminution of the attractive power of
the solenoid on its core, according as the core changes its position within the
solenoid, by means of a chain, a greater or less number of the links of which are
by the movement of the core, brought to act by gravity upon it, substantially as
herein described with reference to Figs. 1, 3 and 4 of the accompanying drawings.
Second Compensating the increase and diminution of the attractive power of
the solenoid according as its core changes its position, by arranging two cores to
balance each other approximately within one solenoid coil, substantially as described
with reference to Fig. 2.
In Witness whereof, I the said Joseph Devonport Finney Andrews have
hereunto set my hand and seal this Twelfth day of January in the year of
Our Lord One thousand, eight hundred and eighty three.