IMPROVEMENTS IN APPARATUS FOR IGNITING AND EX- TINGUISHING A NUMBER OF GAS LAMPS SIMULTANEOUSLY
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by John Muirhead, at the Office of the
Commissioners of Patents on the 9th May 1876. A communication from
abroad by Howard William Warden, of the Public Works Department, Agra,
India
JOHN MUIRHEAD, junior, of Stanley Villa, Thornton Hill, Wimbledon, in the
County of Surrey. "IMPROVEMENTS IN APPARATUS FOR IGNITING AND EX-
TINGUISHING A NUMBER OF GAS LAMPS SIMULTANEOUSLY."
This Invention has for its object the lighting and extinguishing of street and
other lamps simultaneously; electricity is made use of for this purpose. A single.
insulated line wire is laid in iron pipes, so as to form one continuous electrical
circuit beween every lamp and the battery at the main station of each district. At
every lamp is placed an electro-magnet having a primary and a secondary wire.
The primary wire of each electro-magnet forms part of the main circuit.
In the secondary circuits, either the ends of the wire are brought near to cach
other so as to allow sparks to pass across the jet of gas, or the ends are joined
by a spiral of fine platinum wire, which becomes heated sufficiently by the current
to ignite the gas.
There are several methods by which the gas is turned off and on.
In one a
ratchet wheel is attached to the tap of the gas pipe, and below is placed a horizontal
bar carrying a pawl working into the teeth of the ratchet wheel, and having fixed
to it at one end the soft iron armature of the electro-magnet, and to the other end a
spring acting in opposition to the current. In this arrangement by making and
breaking the contact with the battery a certain number of times, the ratchet wheel
is turned the angle required to fully open the tap. The gas is then ignited either
by the sparks across the jet, or the heating of the fine spiral wire caused by the
currents induced in the secondary wire.
To shut off the gas the armature of the electro-magnet is attracted as many more
times until the ratchet wheel is brought back to its original position.
In another arrangement there are two sets of teeth in opposite directions cut on
a part of the circumference of the ratchet wheel. Into these teeth work at
different times two ratchets or a two pronged piece pivotted' at a point above
the horizontal bar carrying the armaturo and working in a slot on a stud fixed to
this bar.

page_text: The ratchet wheel is turned through a fixed angle one way or the other according
to whichever ratchet is in gear. To move these ratchets in and out of gear there is
fixed to one a spring, and the other is connected with the thin flexible cover of an air
chamber which is in communication by means of a pipe, with another air chamber
placed above the burner. On sending a rapid succession of currents through the
primary wire, the ratchet wheel is turned until the tap is fully opened and no
further. The heat from the burning gas causes the air in the air chamber, to
expand and raise the second ratchet into gear, at the same time putting the other
out of gear. On again sending a rapid succession of currents the tap is turned in
the reverse direction through the same angle as before and the gas shut off.