﻿OCEANOGRAPHY 
  — 
  STETSON 
  233 
  

  

  decided 
  to 
  continue 
  them 
  and 
  ordered 
  the 
  construction 
  of 
  another 
  

   nonmagnetic 
  vessel, 
  the 
  Research, 
  to 
  be 
  placed 
  in 
  commission 
  with 
  

   equipment 
  similar 
  to 
  that 
  formerly 
  used 
  on 
  the 
  Carnegie. 
  

  

  GRAVIMETRIC 
  MEASUREMENTS 
  

  

  Attempts 
  to 
  measure 
  gravity 
  at 
  sea 
  by 
  static 
  methods 
  have 
  never 
  

   proved 
  particularly 
  accurate, 
  although 
  many 
  different 
  instruments 
  of 
  

   this 
  type 
  have 
  been 
  devised. 
  The 
  pendulum 
  has 
  always 
  been 
  the 
  

   standard 
  instrument 
  on 
  land; 
  but, 
  because 
  the 
  difficulties 
  of 
  using 
  it 
  

   on 
  board 
  surface 
  ships 
  seemed 
  insurmountable, 
  it 
  was 
  disregarded 
  by 
  

   the 
  earlier 
  workers. 
  In 
  1923 
  the 
  Gravity 
  Survey 
  of 
  Holland 
  began 
  to 
  

   consider 
  the 
  possibilities 
  of 
  using 
  a 
  submarine 
  for 
  this 
  work, 
  and, 
  after 
  

   preliminary 
  tests, 
  the 
  first 
  really 
  accurate 
  measurements 
  were 
  made, 
  on 
  

   board 
  a 
  vessel 
  of 
  this 
  type, 
  by 
  Dr. 
  F. 
  A. 
  Veiling 
  Meinesz, 
  on 
  a 
  cruise 
  

   to 
  the 
  Dutch 
  East 
  Indies. 
  Two 
  pendulums 
  were 
  employed 
  instead 
  of 
  

   one 
  to 
  eliminate 
  the 
  effects 
  of 
  horizontal 
  acceleration. 
  So 
  successful 
  

   was 
  this 
  cruise 
  that, 
  following 
  the 
  lead 
  of 
  the 
  Dutch, 
  similar 
  expedi- 
  

   tions 
  were 
  sent 
  out 
  by 
  other 
  countries. 
  Since 
  1928 
  the 
  United 
  States 
  

   Navy 
  on 
  three 
  separate 
  occasions, 
  in 
  cooperation 
  with 
  Princeton 
  Uni- 
  

   versity, 
  has 
  dispatched 
  a 
  submarine 
  for 
  surveys 
  in 
  the 
  West 
  Indies, 
  

   and 
  the 
  French, 
  Italians, 
  Russians, 
  and 
  Japanese 
  one 
  or 
  more 
  each 
  to 
  

   the 
  Mediterranean, 
  Black 
  Sea, 
  and 
  the 
  Far 
  East. 
  The 
  Netherlands, 
  

   in 
  the 
  meantime, 
  has 
  completed 
  seven 
  additional 
  surveys 
  and 
  is 
  about 
  

   to 
  send 
  out 
  an 
  eighth. 
  The 
  original 
  apparatus 
  has, 
  of 
  course, 
  been 
  

   considerably 
  modified 
  and 
  refined 
  since 
  the 
  first 
  model 
  was 
  constructed, 
  

   but 
  the 
  Meinesz 
  method 
  has 
  been 
  followed 
  in 
  all 
  this 
  work. 
  

  

  As 
  in 
  the 
  case 
  of 
  terrestrial 
  magnetism, 
  not 
  only 
  is 
  it 
  desirable 
  to 
  

   extend 
  the 
  measurement 
  of 
  gravity 
  to 
  the 
  oceans 
  so 
  that 
  the 
  areal 
  sur- 
  

   vey 
  of 
  the 
  earth 
  may 
  be 
  as 
  extensive 
  as 
  possible, 
  but 
  in 
  this 
  particular 
  

   case 
  fundamental 
  data 
  can 
  be 
  gathered 
  at 
  sea 
  that 
  cannot 
  be 
  obtained 
  

   on 
  land. 
  The 
  discovery 
  of 
  the 
  large 
  negative 
  anomalies 
  in 
  the 
  vicinity 
  

   of 
  island 
  arcs 
  and 
  fore 
  deeps 
  has 
  greatly 
  influenced 
  our 
  ideas 
  on 
  the 
  

   processes 
  involved 
  in 
  mountain 
  building 
  and 
  gives 
  another 
  clue 
  as 
  to 
  

   what 
  may 
  have 
  happened 
  in 
  depth 
  during 
  deformation. 
  Solving 
  the 
  

   problem 
  of 
  measuring 
  gravity 
  at 
  sea 
  may 
  be 
  ranked 
  as 
  one 
  of 
  the 
  major 
  

   contributions 
  of 
  geophysics 
  to 
  geology 
  in 
  recent 
  years 
  (Vening 
  

   Meinesz, 
  1930; 
  1934). 
  

  

  SEISMIC 
  TECHNIQUE 
  

  

  The 
  importance 
  of 
  seismic 
  techniques 
  as 
  an 
  aid 
  to 
  structural 
  geology 
  

   has 
  long 
  been 
  recognized, 
  but 
  the 
  practical 
  difficulties 
  which 
  stood 
  in 
  

   the 
  way 
  of 
  the 
  adaptation 
  of 
  this 
  well-known 
  procedure 
  to 
  marine 
  

   conditions 
  long 
  delayed 
  its 
  use 
  at 
  sea. 
  It 
  is 
  the 
  most 
  recent 
  of 
  the 
  three 
  

   geophysical 
  methods 
  to 
  be 
  applied 
  to 
  oceanic 
  problems. 
  The 
  first 
  

  

  