Low-Pressure  Circuit. — A  circuit  de-
signed for  use  in  connection  with  low
electric  pressure.
Low-Pressure  Incandescent  Lamp.—
An  incandescent  lamp  whose  filament  is
short  and  thick,  and,  consequently,  of


low  electric  resistance  suited  for  a  lo\*
pressure.
Low-Resistance  Magnet.  —  A  magnet
wound  with  low-resistance  magnetizing
coils.
Low-Speed  Electric  Motor.— An  elec-
tric motor  designed  to  run  normally  at
low  speeds.
Low  Tension. — A  term  sometimes  used

for  low  pressure.
Low-Tension  Bus.— In  a  central  station

any  bus-bar  connected  witli  a  low-tension

generator.
Low-Tension  Electric  Fuse.— A  fuse
that  is  ignited  by  heating  a  wire  to  in-
candescence by  the  passage  of  an  electric
current  of  low  pressure,  as  distinguished
from  a  high-tension  fuse.
Low-Tension  Switch.  —  A  switch  de-
signed for  use  on  low-tension  circuits.
Low  Vacuum. — (1)  A  vacuum  in  which
the  mean-free-path  of  the  molecules  of
the  residual  gas  is  small  as  compared  with
the  dimensions  of  the  containing  vessel.
(2)  A  space  from  which  only  a  portion  ot~
the  air  or  residual  gas  has  been  removed.
Loxodograph. — An  apparatus  for  elec-
trically recording  on  paper  the  actual
course  of  a  ship,  by  the  combined  action
of  magnetism  and  photography.
Lubricating. — Reducing  friction  by
means  of  lubrication.
Lubrication. — The  reduction  of  friction
between  surfaces,  by  rendering  them
slippery.
Luces. — A  plural  of  lux.
Lumen. — (1)  A  unit  of  flux-of-light  equal
to  the  light  received  by  a  square  metre  of
spherical  surface,  from  a  point  source  of
unit  intensity,  placed  at  the  centre  of  a
sphere  one  metre  in  radius.  (2)  The  flux
of  light  through  a  steradian  from  a  point
source,  whose  intensity  is  one  pyr.  (3)  A
pyr-steradian.
Lumen-Meter. — An  instrument  for  meas-
uring the  flux  of  light.
Lumen-Second. — A  rad.
