﻿434 
  ANNUAL 
  REPOET 
  SMITHSONIAN 
  INSTITUTION, 
  192 
  9 
  

  

  received. 
  If 
  man 
  is 
  to 
  be 
  master 
  of 
  his 
  destiny, 
  to 
  "live 
  well", 
  and 
  

   "to 
  conquer 
  nature 
  by 
  observance 
  of 
  her 
  laws", 
  these 
  are 
  the 
  secrets 
  

   which 
  he 
  has 
  now 
  to 
  learn. 
  

  

  The 
  problem 
  at 
  this 
  moment 
  seems 
  to 
  offer 
  two 
  main 
  lines 
  of 
  

   attack 
  — 
  to 
  find 
  the 
  causes 
  of 
  the 
  alternate 
  (300-year) 
  periods 
  of 
  

   migration 
  and 
  consolidation, 
  and 
  to 
  determine 
  the 
  chronology 
  and 
  

   causes 
  of 
  the 
  glacial 
  periods. 
  Both 
  solutions 
  are 
  for 
  the 
  present 
  

   veiled 
  in 
  obscurity. 
  

  

  The 
  conclusions 
  so 
  far 
  reached 
  suggest 
  an 
  examination 
  of 
  all 
  

   phenomena 
  likely 
  to 
  be 
  related 
  throughout 
  the 
  whole 
  field 
  of 
  scientific 
  

   inquiry, 
  and 
  primarily 
  in 
  those 
  branches 
  of 
  knowledge 
  classified 
  as 
  

   geology 
  and 
  meteorology. 
  

  

  In 
  the 
  sciences 
  concerned 
  with 
  the 
  study 
  of 
  past 
  events, 
  in 
  geology, 
  

   paleo-climatology 
  and 
  archeology, 
  as 
  in 
  history, 
  a 
  clear 
  arrangement 
  

   of 
  the 
  facts 
  is 
  impossible 
  without 
  a 
  standard 
  for 
  the 
  measurement 
  of 
  

   time. 
  The 
  need 
  for 
  such 
  a 
  standard 
  has 
  long 
  been 
  felt 
  by 
  geologists. 
  

   Nearly 
  a 
  century 
  ago 
  they 
  sought 
  the 
  aid 
  of 
  the 
  astronomers 
  in 
  an 
  

   attempt 
  to 
  give 
  definition 
  to 
  geological 
  time. 
  No 
  solution 
  has 
  been 
  

   found 
  on 
  those 
  lines. 
  In 
  Climate 
  Through 
  the 
  Ages, 
  Brooks 
  elucidates 
  

   many 
  of 
  the 
  phenomena 
  connected 
  with 
  the 
  great 
  glaciations, 
  buf 
  he 
  

   shows 
  that 
  questions 
  of 
  chronology 
  are 
  still 
  in 
  doubt. 
  One 
  possible 
  

   factor 
  in 
  the 
  equation, 
  which 
  is 
  still 
  unknown 
  in 
  spite 
  of 
  observations 
  

   dating 
  from 
  Ptolemy's 
  time, 
  is 
  the 
  variation 
  in 
  the 
  obliquity 
  of 
  the 
  

   ecliptic. 
  If 
  more 
  were 
  known 
  about 
  the 
  periods, 
  extent, 
  and 
  nature 
  

   of 
  this 
  variation, 
  and 
  its 
  exact 
  relation, 
  if 
  any, 
  to 
  changes 
  of 
  climate, 
  

   we 
  should 
  be 
  nearer 
  a 
  solution 
  of 
  the 
  questions 
  connected 
  with 
  the 
  

   passing 
  of 
  the 
  last 
  glaciation, 
  and 
  the 
  progress 
  from 
  paleolithic 
  to 
  

   neolithic 
  civilization 
  which 
  accompanied 
  it. 
  Assuming 
  that 
  the 
  

   "primary 
  tendency" 
  for 
  civilization 
  to 
  move 
  away 
  from 
  the 
  equator 
  

   is 
  connected 
  with 
  the 
  glacial 
  cycle, 
  we 
  should 
  be 
  nearer 
  to 
  under- 
  

   standing 
  whether 
  and 
  when 
  the 
  centers 
  of 
  civilization 
  are 
  likely 
  to 
  

   pass 
  south 
  again. 
  

  

  Similarly 
  it 
  is 
  tempting 
  to 
  hope 
  that 
  the 
  inference 
  of 
  a 
  640-year 
  

   cycle 
  may 
  be 
  supplemented 
  by 
  evidence 
  as 
  to 
  its 
  origin. 
  If 
  it 
  were 
  

   established, 
  it 
  would 
  facilitate 
  the 
  study 
  of 
  future, 
  as 
  well 
  as 
  of 
  

   archeological, 
  problems. 
  

  

  Whether 
  this 
  inference 
  of 
  a 
  regular 
  periodicity 
  is 
  true 
  or 
  not, 
  

   the 
  fact 
  of 
  the 
  occurrence 
  of 
  long 
  periods 
  of 
  drought 
  and 
  disturbance 
  

   on 
  the 
  one 
  hand, 
  and 
  of 
  climatically 
  and 
  economically 
  "settled" 
  

   conditions 
  on 
  the 
  other 
  is 
  susceptible 
  of 
  scientific 
  explanation. 
  The 
  

   problem 
  will 
  be 
  solved 
  eventually, 
  if 
  only 
  because 
  a 
  knowledge 
  of 
  

   all 
  the 
  factors 
  will 
  make 
  it 
  possible 
  to 
  foresee 
  and 
  provide 
  for 
  future 
  

   catastrophes. 
  

  

  The 
  main 
  factors 
  as 
  known 
  at 
  present 
  appear 
  to 
  be 
  variations 
  in 
  

   the 
  position 
  and 
  intensity 
  of 
  the 
  north 
  temperate 
  storm 
  belt 
  and 
  in 
  

  

  