Switch, Knife.
A switch whose movable arm is a narrow, deep bar of copper or brass, and
which in making contact is forced in edgeways between two springs
connected to one terminal. The bar is connected to the other terminal.
Synonyms--Knife Break Switch--Knife Edge Switch.
Switch, Multiple.
A switch which in the swing of its bar connects one by one with a number
of contacts so that ultimately the end of its bar is in contact with all
at once. It is used to throw lights in and out in succession, and it
can, if the multiple contacts connect with resistances, make them
operate as a rheostat.
Switch, Pole Changing.
A switch for changing the direction of the current in a circuit.
Switch, Reversing.
A switch, often of the plug type (see Plug Switch) for changing the
direction of current passing through a galvanometer.
Switch, Snap.
A switch constructed to give a quick, sharp break. It has a spiral
spring interposed between the handle and arm. As the handle is drawn
back to open it the spring is first extended, the bar being held by the
friction of the contacts, until the spring suddenly jerks it up, thus
breaking the contact.
Switch, Storage Battery Changing.
A switch for changing storage battery connections from series to
multiple and back again.
Switch, Three Way.
A switch, so constructed that by turning its handle connection can be
made from one lead to either of two other leads, and also so that
connection can be completely cut off.
Sympathetic Vibration.
The establishment of periodic movement in one body by impulses of the
same period communicated to it from another body in motion. Thus if two
tuning forks are of the same pitch and one is sounded the other will
begin to sound by sympathy, the sound waves communicating the necessary
periodic impulses to it.
Sympathetic vibrations are utilized in harmonic telegraphy. (See
Harmonic Receiver--Telegraph, Harmonic.)
T.
Symbol of time.
Tailings.
(a) In high speed transmission of telegraph signals by the automatic
system, the definiteness of the signal marks is sometimes interfered
with by retardation. Wrong marks are thus produced called tailings.
(b) The prolongation of the current at the distant receiving station of
a telegraph line due to the discharge of the line and to self-induction.
Synonyms--Tailing--Tailing Current.