IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1878

page_text: .
PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office of
the Commissioners of Patents on the 9th December 1878. A. communication
from abroad by François Ernest de Mersanne and Emile Bertin, both of Paris,
in the Republic of France.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN ELECTRIC LAMPS." A communication from abroad
by François Ernest de Mersanne and Emile Bertin, both of Paris, in the Republic
of France.
This Invention relates to the construction of lamps more particularly adapted
for the production of small lights for lighting the interior of dwellings by the
incandescence of carbons.
These lamps may be arranged on one circuit or on separate circuits, along which
the current is caused to pass in succession by a commutator.
In carrying out this Invention the light is produced by the incandescence of
charcoal, and may be made of considerable intensity when required.
The lamp is mounted upon a wooden stand carrying a brass socket surmounted
by a ring also of brass; a plug of silicate of magnesia (for example) or other
refractory material is placed in this socket, and is traversed by a netal wire of
about the same diameter as the conductor, terminating in a finer platinum wire.
On the upper part of the ring are arranged radially two or more tubes, in the
interior of each of which is provided a carbon rod carrying a weight, which presses
it against the end of the platinum wire inserted in the socket when in action,
whilst when out of action the rod is supported at a suitable distance from the end
of the wire by a suitable arrangement of catch and lever. Two small spring jaws
of platinum are employed, which press against the carbon rod in order to maintain
the contact. The current enters the apparatus at one side of the stand and leaves
it at the opposite side. When the current is passing, the part of the carbon rod
which is exposed between the jaws and the extremity of the platinum wire, is in a
state of incandescence, and is even capable of melting the end of the wire.
Assuming that two carbon rods are employed when one of the rods is consumed,
the weight upon this rod in descending comes in contact with the catch and lever
Price 271

page_text: herein before referred to and moves it, so as to release the other rod, which is then
brought into contact with the end of the platinum wire, and becomes incandescent
in its turn as the descent of the weight on the rod first consumed is arrested by a
suitable stop; this rod soon ceases to be in contact with the platinum wire. Whilst
the second carbon is consuming, the catch and lever arrangement is turned round,
so as to support a third carbon rod, which takes the place of the one first con-
sumed until it is released by the descent of the weight on the second rod, which is
then to be replaced by a fourth rod, and so on in succession. This automatic
apparatus also operates in a like manner in the event of one of the carbons
becoming broken.
If required the catch and lever devices hereinbefore referred to may be worked
by a magnet of resistance connected with the current in lieu of by the weights on
the rods. The electric magnet offering most resistance to the passage of the current
would actuate with its armature the lever devices when one of the carbons is
almost or entirely consumed.
The length of the part of the carbon which is in a state of incandescence may be
adjusted as required by screwing up or unscrewing the conducting tubes on the
brass ring.