II. The deflecting force, although variable in its direction in space,
is fixed in direction relatively to the deflecting body.
Single Fluid Theory.
A theory of electricity. Electricity, as has been said, being
conveniently treated as a fluid or fluids, the single fluid theory
attributes electrical phenomena to the presence or absence of a single
fluid. The fluid repels itself but attracts matter; an excess creates
positive, a deficiency, negative electrification; friction, contact
action or other generating cause altering the distribution creates
potential difference or electrification. The assumed direction (see
Direction) of the current and of lines of force are based on the single
fluid theory. Like the double fluid theory, q. v., it is merely a
convenience and not the expression of a truth. (See Fluid, Electric, and
Double Fluid Theory.)
Synonym--Franklin's Theory.
Single Fluid Voltaic Cell.
A galvanic couple using only a single fluid, such as the Smee or Volta
cell.
Simple Harmonic Motion.
Motion of a point or body back and forth along a line; the motion of a
pendulum, as regards its successive swings back and forth, is an example
of harmonic motion.
Sinistrotorsal. adj.
The reverse of dextrotorsal, q. v. A helix with left-handed winding, the
reverse of an ordinary screw, such as a wood-screw or corkscrew.
Skin Effect.
A current of very brief duration does not penetrate the mass of a
conductor. Alternating currents for this reason are mainly conducted by
the outer layers of a conductor. The above is sometimes called the skin
effect.
Sled.
A contact for electric cars of the conduit system. It is identical with
the plow, q.v., but is drawn after the cars instead of being pushed
along with them.
Slide Meter Bridge.
A name for a Slide Bridge one meter long. There are also slide half
meter and slide quarter meter bridges and others. (See Meter Bridge.)
S. N. Code.
Abbreviation for single needle code, the telegraphic alphabet used with
the single needle system.
Soaking-in-and-out.
A term for the phenomena of the residual electrostatic charge; the
gradual acquirement or loss by a condenser of a portion of its
electrostatic charge.