Spiral.
This term is sometimes used instead of coil, as the primary spiral or
secondary spiral of an induction coil or transformer.
Spiral Winding.
The winding used on ring armatures. This may diagrammatically be
represented by a spiral carried around the ring shaped core. With two
field poles it gives two collecting points, positive and negative, with
four field poles it gives four collecting points, alternately positive
and negative.
Splice Box.
A box in which the splices in underground cables and electric lines are
contained. The splicing is generally done in the boxes with the cables
in place. They may be two-way for straight lines, or be four-way for two
side or lateral connections.
Spluttering.
A term applied to a sound sometimes produced in a voltaic arc, perhaps
caused by impure or insufficiently baked electrodes. (Elihu Thomson.)
Spring Control.
Control of or giving the restitutive force to the needle of a
galvanometer, core of a solenoid ammeter or moving part of any similar
instrument by a spring. As an example see Ammeter, Ayrton's.
Fig. 307. SPRING JACKS.
Spring Jack.
An arrangement for effecting, at one insertion of a species of plug, the
opening or breaking of a circuit and for the simultaneous connection to
the terminals formed by the breaking of two terminals of another system
or loop. Thus let a line include in its circuit two springs pressing
against each other, thereby completing the circuit. If a plug or wedge
of insulating material were inserted between the springs so as to press
them apart it would break the circuit and the whole would constitute a
spring jack cut-out. If each side of the plug had a strip of brass or
copper attached to it, and if the ends of another circuit were connected
to these strips, then the insertion of the plug would throw the new line
into the circuit of the other line.