Logarithm.
The exponent of the power to which it is necessary to raise a fixed
number to produce a given number. The fixed number is the base of the
system. There are two systems; one, called the ordinary system, has 10
for its base, the other, called the Naperian system, has 2.71828 for its
base. The latter are also termed hyperbolic logarithms, and are only
used in special calculations.
Log, Electric.
An apparatus for measuring the speed of a ship. A rotating helical vane
of known pitch is dragged behind the vessel. As the helix rotates its
movements may actuate electric machinery for registering its rotations.
The number of these in a given time, multiplied by the pitch of the
vane, gives the distance traversed in such time.
Loop.
A portion of a circuit introduced in series into another circuit. The
latter circuit is opened by a spring-jack, q. v. or other device, and
the loop inserted. By loops any number of connections can be inserted
into a circuit in series therewith, and in series or in parallel with
one another.
Loop Break.
A double bracket or similar arrangement for holding on insulators the
ends of a conductor which is cut between them, and to which are
connected the ends of a loop. The space between the insulators may be
about a foot.
Luces.
This may be used as the plural of lux, q. v. It is the Latin plural.
Luminous Jar.
A Leyden jar whose coatings are of lozenge-shaped pieces of tinfoil
between which are very short intervals. When discharged, sparks appear
all over the surface where the lozenges nearly join.
Lux.
A standard of illumination, q. v., as distinguished from illuminating
power.
It is the light given by one candle at a distance of 12.7 inches--by a
carcel, q. v., at a distance of one meter---or by 10,000 candles at
105.8 feet.
It was proposed by W. H. Preece. All the above valuations are identical.
M.
(a) Symbol of gaseous pressure equal to one-millionth of an atmosphere.
(b) The Greek m, µ, is used as the symbol of magnetic permeability.