﻿APR. 
  4, 
  1922 
  PROCEEDINGS 
  : 
  PHILOSOPHICAL 
  SOCIETY 
  187 
  

  

  tion 
  component 
  that 
  correspond 
  with 
  the 
  small 
  gradations 
  (say 
  B2 
  and 
  B8) 
  in 
  

   spectral 
  classes. 
  

  

  For 
  binary 
  stars 
  having 
  companions 
  of 
  low 
  luminosity 
  the 
  water-cell 
  

   transmissions 
  are 
  low, 
  indicating 
  that 
  the 
  companion 
  stars 
  emit 
  considerable 
  

   infra-red 
  radiation. 
  

  

  Among 
  the 
  subsidiary 
  investigations 
  made 
  with 
  a 
  view 
  to 
  the 
  improvement 
  

   of 
  stellar 
  radiometers, 
  the 
  complete 
  paper 
  gives 
  data 
  on 
  the 
  radiation 
  sensitiv- 
  

   ity 
  of 
  thermocouples 
  of 
  alloys 
  of 
  gold-palladium, 
  platinum-rhodium, 
  bismuth- 
  

   tin, 
  bismuth-antimon}^, 
  and 
  also 
  of 
  pure 
  bismuth. 
  

  

  In 
  conclusion, 
  it 
  is 
  relevant 
  to 
  note 
  that 
  in 
  comparison 
  with 
  the 
  photo- 
  

   electric 
  cell 
  the 
  thermocouple 
  is 
  far 
  less 
  sensitive, 
  and 
  hence 
  the 
  number 
  of 
  

   stars 
  that 
  can 
  be 
  measured 
  by 
  it 
  is 
  more 
  limited. 
  Neither 
  instrument 
  can 
  

   tell 
  us 
  the 
  size 
  or 
  distance 
  of 
  stars. 
  The 
  thermocouple 
  enables 
  one 
  to 
  obtain 
  

   information 
  not 
  obtainable 
  by 
  other 
  instruments. 
  Combined 
  with 
  an 
  ab- 
  

   sorption 
  cell 
  (of 
  water) 
  one 
  can 
  detect 
  the 
  presence 
  of 
  dark 
  companions 
  of 
  

   binary 
  stars. 
  This 
  device 
  also 
  gives 
  us 
  a 
  new 
  means 
  for 
  studying 
  planetary 
  

   radiation 
  and 
  temperature 
  conditions. 
  If 
  the 
  surface 
  of 
  a 
  planet 
  becomes 
  

   warmed 
  by 
  the 
  sun's 
  rays, 
  and 
  in 
  turn 
  emits 
  radiation 
  (which 
  will 
  be 
  entirely 
  of 
  

   long 
  wave-lengths) 
  the 
  amount 
  of 
  radiation 
  transmitted 
  through 
  the 
  water 
  

   cell 
  will 
  be 
  less 
  than 
  when 
  the 
  reflecting 
  surface 
  remains 
  cool. 
  Data 
  of 
  this 
  

   type 
  were 
  previously 
  obtained 
  on 
  the 
  moon. 
  Applied 
  to 
  the 
  planet 
  Mars, 
  if 
  

   the 
  polar 
  cap 
  is 
  snow, 
  then 
  the 
  transmission 
  of 
  reflected 
  sunlight 
  should 
  be 
  

   higher 
  than 
  that 
  observed 
  from 
  the 
  dark 
  areas, 
  if 
  the 
  latter 
  are 
  bare 
  ground. 
  

   On 
  the 
  other 
  hand, 
  if 
  the 
  dark 
  areas 
  contain 
  green 
  vegetation 
  (similar 
  to 
  that 
  

   of 
  our 
  earth) 
  the 
  temperature 
  rise 
  will 
  be 
  small, 
  the 
  water-cell 
  transmission 
  

   will 
  be 
  high, 
  and 
  the 
  results 
  may 
  be 
  difficult 
  of 
  interpretation. 
  

  

  Paltl 
  D. 
  Foote, 
  F. 
  L. 
  Mohler 
  and 
  W. 
  F. 
  Meggers: 
  "A 
  significant 
  ex- 
  

   ception 
  to 
  the 
  principle 
  of 
  selection" 
  (presented 
  by 
  Mr. 
  Foote 
  and 
  illustrated). 
  

   The 
  paper 
  was 
  discussed 
  by 
  Mr. 
  Hawksworth. 
  

  

  The 
  pair 
  Is 
  — 
  3d 
  of 
  sodium 
  and 
  potassium, 
  in 
  Sommerfeld's 
  theory 
  necessi- 
  

   tates 
  an 
  interorbital 
  transition 
  where 
  the 
  change 
  in 
  azimuthal 
  quantum 
  num- 
  

   ber 
  is 
  two 
  units. 
  The 
  presence 
  of 
  this 
  pair 
  has 
  always 
  been 
  attributed 
  to 
  

   the 
  incipient 
  Stark 
  effect 
  of 
  the 
  exciting 
  field. 
  In 
  the 
  present 
  paper 
  an 
  ex- 
  

   perimental 
  arrangement 
  is 
  described 
  wherein 
  the 
  radiation 
  is 
  completely 
  

   shielded 
  from 
  the 
  applied 
  field, 
  itself 
  only 
  7 
  volts. 
  The 
  pair 
  may 
  then 
  be 
  

   produced 
  at 
  will 
  by 
  increasing 
  the 
  exciting 
  current 
  until 
  it 
  is 
  one 
  of 
  the 
  strong- 
  

   est 
  lines 
  of 
  the 
  spectrum. 
  It 
  therefore 
  is 
  an 
  exception 
  to 
  the 
  selection 
  prin- 
  

   ciple 
  which 
  cannot 
  be 
  explained 
  away 
  by 
  a 
  Stark 
  effect. 
  Its 
  explanation 
  is 
  of 
  

   deeper 
  origin, 
  possibly 
  requiring 
  a 
  reconsideration 
  of 
  the 
  method 
  whereby 
  

   single 
  azimuthal 
  quantum 
  numbers 
  have 
  been 
  assigned 
  to 
  each 
  of 
  the 
  s, 
  p, 
  d 
  

   and 
  b 
  terms. 
  

  

  Walter 
  P. 
  White: 
  Some 
  precision 
  pendulums 
  (illustrated). 
  The 
  paper 
  

   was 
  discussed 
  by 
  Messrs. 
  Pawling, 
  Press, 
  Tuckerman 
  and 
  Silsbee. 
  

  

  Pendulums 
  are 
  practically 
  always 
  driven 
  by 
  a 
  push 
  in 
  the 
  direction 
  of 
  

   motion. 
  This 
  may 
  take 
  two 
  forms 
  : 
  (1) 
  A 
  direct 
  push 
  is 
  given 
  symmetrically 
  

   about 
  the 
  middle 
  of 
  the 
  stroke. 
  This 
  is 
  usually 
  done 
  by 
  force 
  applied 
  at 
  

   right 
  angles 
  to 
  the 
  direction 
  of 
  motion, 
  acting 
  on 
  an 
  inclined 
  surface 
  (pallet). 
  

   This 
  method 
  involves 
  considerable 
  friction 
  and 
  consequent 
  possibility 
  of 
  

   irregularity. 
  (2) 
  The 
  pendulum 
  meets 
  and 
  pushes 
  against 
  a 
  pallet 
  which 
  

   acts 
  on 
  an 
  opposing 
  weight 
  or 
  spring, 
  and 
  which 
  follows 
  the 
  pendulum 
  in 
  the 
  

   return 
  to 
  a 
  point 
  beyond 
  that 
  at 
  which 
  it 
  was 
  picked 
  up. 
  The 
  opposing 
  pallet 
  

  

  