Filament.
A thin long piece of a solid substance. In general it is so thin as to
act almost like a thread, to be capable of standing considerable
flexure. The distinction between filament and rod has been of much
importance in some patent cases concerning incandescent lamps. As used
by electricians the term generally applies to the carbon filament of
incandescent lamps. This as now made has not necessarily any fibres, but
is entitled to the name of filament, partly by convention, partly by its
relative thinness and want of stiffness. (See Incandescent
Lamps--Magnetic Filament.)
Fire Alarm, Electric, Automatic.
A system of telegraph circuits, at intervals supplied with thermostats
or other apparatus affected by a change of temperature, which on being
heated closes the circuit and causes a bell to ring. (See Thermostat.)
Fire Alarm Telegraph System.
A system of telegraphic lines for communicating the approximate location
of a fire to a central station and thence to the separate fire-engine
houses in a city or district. It includes alarm boxes, distributed at
frequent intervals, locked, with the place where the key is kept
designated, or in some systems left unlocked. On opening the door of the
box and pulling the handle or otherwise operating the alarm, a
designated signal is sent to the central station. From this it is
telegraphed by apparatus worked by the central station operator to the
engine houses. The engines respond according to the discipline of the
service.
Fire Cleansing.
Freeing the surface of an article to be plated from grease by heating.
Fire Extinguisher, Electric, Automatic.
A modification of the electric fire alarm (see Fire Alarm, Electric,
Automatic), in which the thermostats completing the circuits turn on
water which, escaping through the building, is supposed to reach and
extinguish a fire.
Flashing in a Dynamo or Magneto-electric Generator.
Bad adjustment of the brushes at the commutator, or other fault of
construction causes the production of voltaic arcs at the commutator of
a generator, to which the term flashing is applied.
Flashing of Incandescent Lamp Carbons.
A process of treatment for the filaments of incandescent lamps. The
chamber before sealing up is filled with a hydro-carbon vapor or gas,
such as the vapor of a very light naphtha (rhigolene). A current is then
passed through the filament heating it to redness. The more attenuated
parts or those of highest resistance are heated the highest, and
decompose most rapidly the hydro-carbon vapor, graphitic carbon being
deposited upon these parts, while hydrogen is set free. This goes on
until the filament is of uniform resistance throughout. It gives also a
way of making the resistance of the filament equal to any desired number
of ohms, provided it is originally of high enough resistance. The
process increases the conductivity of the filament.
After flashing the chambers are pumped out and sealed up.