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longitudemore about longitude


  4  definitions  found 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
  Longitude  \Lon"gi*tude\,  n.  [F.,  fr  L.  longitudo,  fr  longus 
  1.  Length;  measure  or  distance  along  the  longest  line  -- 
  distinguished  from  breadth  or  thickness;  as  the  longitude 
  of  a  room  rare  now  except  in  a  humorous  sense  --Sir  H. 
  The  longitude  of  their  cloaks.  --Sir.  W. 
  Mine  [shadow]  spindling  into  longitude  immense. 
  2.  (Geog.)  The  arc  or  portion  of  the  equator  intersected 
  between  the  meridian  of  a  given  place  and  the  meridian  of 
  some  other  place  from  which  longitude  is  reckoned,  as  from 
  Greenwich,  England,  or  sometimes  from  the  capital  of  a 
  country,  as  from  Washington  or  Paris.  The  longitude  of  a 
  place  is  expressed  either  in  degrees  or  in  time;  as  that 
  of  New  York  is  74[deg]  or  4  h.  56  min.  west  of  Greenwich. 
  3.  (Astron.)  The  distance  in  degrees,  reckoned  from  the 
  vernal  equinox,  on  the  ecliptic,  to  a  circle  at  right 
  angles  to  the  ecliptic  passing  through  the  heavenly  body 
  whose  longitude  is  designated;  as  the  longitude  of 
  Capella  is  79[deg]. 
  {Geocentric  longitude}  (Astron.),  the  longitude  of  a  heavenly 
  body  as  seen  from  the  earth. 
  {Heliocentric  longitude},  the  longitude  of  a  heavenly  body, 
  as  seen  from  the  sun's  center. 
  {Longitude  stars},  certain  stars  whose  position  is  known  and 
  the  data  in  regard  to  which  are  used  in  observations  for 
  finding  the  longitude,  as  by  lunar  distances. 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
  Refraction  \Re*frac"tion\  (r?*fr?k"sh?n),  n.  [F.  r['e]fraction.] 
  1.  The  act  of  refracting,  or  the  state  of  being  refracted. 
  2.  The  change  in  the  direction  of  ray  of  light,  heat,  or  the 
  like  when  it  enters  obliquely  a  medium  of  a  different 
  density  from  that  through  which  it  has  previously  moved 
  Refraction  out  of  the  rarer  medium  into  the  denser, 
  is  made  towards  the  perpendicular.  --Sir  I. 
  3.  (Astron.) 
  a  The  change  in  the  direction  of  a  ray  of  light,  and 
  consequently,  in  the  apparent  position  of  a  heavenly 
  body  from  which  it  emanates,  arising  from  its  passage 
  through  the  earth's  atmosphere;  --  hence  distinguished 
  as  atmospheric  refraction,  or  astronomical  refraction. 
  b  The  correction  which  is  to  be  deducted  from  the 
  apparent  altitude  of  a  heavenly  body  on  account  of 
  atmospheric  refraction,  in  order  to  obtain  the  true 
  {Angle  of  refraction}  (Opt.),  the  angle  which  a  refracted  ray 
  makes  with  the  perpendicular  to  the  surface  separating  the 
  two  media  traversed  by  the  ray. 
  {Conical  refraction}  (Opt.),  the  refraction  of  a  ray  of  light 
  into  an  infinite  number  of  rays,  forming  a  hollow  cone. 
  This  occurs  when  a  ray  of  light  is  passed  through  crystals 
  of  some  substances,  under  certain  circumstances.  Conical 
  refraction  is  of  two  kinds;  external  conical  refraction, 
  in  which  the  ray  issues  from  the  crystal  in  the  form  of  a 
  cone,  the  vertex  of  which  is  at  the  point  of  emergence; 
  and  internal  conical  refraction,  in  which  the  ray  is 
  changed  into  the  form  of  a  cone  on  entering  the  crystal, 
  from  which  it  issues  in  the  form  of  a  hollow  cylinder. 
  This  singular  phenomenon  was  first  discovered  by  Sir  W.  R. 
  Hamilton  by  mathematical  reasoning  alone,  unaided  by 
  {Differential  refraction}  (Astron.),  the  change  of  the 
  apparent  place  of  one  object  relative  to  a  second  object 
  near  it  due  to  refraction;  also  the  correction  required 
  to  be  made  to  the  observed  relative  places  of  the  two 
  {Double  refraction}  (Opt.),  the  refraction  of  light  in  two 
  directions,  which  produces  two  distinct  images.  The  power 
  of  double  refraction  is  possessed  by  all  crystals  except 
  those  of  the  isometric  system.  A  uniaxial  crystal  is  said 
  to  be  optically  positive  (like  quartz),  or  optically 
  negative  (like  calcite),  or  to  have  positive,  or  negative, 
  double  refraction,  according  as  the  optic  axis  is  the  axis 
  of  least  or  greatest  elasticity  for  light;  a  biaxial 
  crystal  is  similarly  designated  when  the  same  relation 
  holds  for  the  acute  bisectrix. 
  {Index  of  refraction}.  See  under  {Index}. 
  {Refraction  circle}  (Opt.),  an  instrument  provided  with  a 
  graduated  circle  for  the  measurement  of  refraction. 
  {Refraction  of  latitude},  {longitude},  {declination},  {right 
  ascension},  etc.,  the  change  in  the  apparent  latitude, 
  longitude,  etc.,  of  a  heavenly  body,  due  to  the  effect  of 
  atmospheric  refraction. 
  {Terrestrial  refraction},  the  change  in  the  apparent  altitude 
  of  a  distant  point  on  or  near  the  earth's  surface,  as  the 
  top  of  a  mountain,  arising  from  the  passage  of  light  from 
  it  to  the  eye  through  atmospheric  strata  of  varying 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
  Heliocentric  \He`li*o*cen"tric\,  Heliocentrical 
  \He`li*o*cen"tric"al\,  a.  [Helio-  +  centric,  centrical:  cf  F. 
  h['e]liocentrique.]  (Astron.) 
  pertaining  to  the  sun's  center,  or  appearing  to  be  seen  from 
  it  having  or  relating  to  the  sun  as  a  center;  --  opposed 
  to  geocentrical. 
  {Heliocentric  parallax}.  See  under  {Parallax}. 
  {Heliocentric  place},  {latitude},  {longitude},  etc  (of  a 
  heavenly  body),  the  direction,  latitude,  longitude,  etc., 
  of  the  body  as  viewed  from  the  sun. 
  From  WordNet  r  1.6  [wn]: 
  n  :  an  imaginary  great  circle  on  the  surface  of  the  earth 
  passing  through  the  north  and  south  poles  at  right  angles 
  to  the  equator;  "all  points  on  the  same  meridian  have  the 
  same  longitude"  [syn:  {meridian},  {line  of  longitude}] 

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