﻿24 
  PROCEEDINGS 
  OF 
  THE 
  CALIFORNIA 
  

  

  that 
  we 
  cannot, 
  from 
  it 
  alone, 
  predicate 
  any 
  periodicity. 
  Even 
  the 
  well 
  marked 
  

   short 
  period 
  of 
  comparatively 
  little 
  rainfall 
  and 
  of 
  clear 
  weather 
  during 
  each 
  of 
  

   our 
  wet 
  seasons, 
  is 
  masked 
  in 
  the 
  averages 
  of 
  monthly 
  rainfall 
  in 
  these 
  years 
  by 
  

   its 
  not 
  occurring 
  at 
  any 
  well 
  defined 
  epoch. 
  But 
  its 
  existence 
  is 
  well 
  marked 
  

   and 
  established 
  in 
  the 
  illustration 
  of 
  the 
  monthly 
  rainfall 
  from 
  1849 
  to 
  the 
  

   present, 
  

  

  [In 
  the 
  graphical 
  illustration 
  of 
  the 
  rainfall 
  at 
  San 
  Francisco, 
  the 
  vertical 
  

   black 
  lines 
  shown 
  in 
  fig. 
  1 
  indicate 
  the 
  inches 
  of 
  rainfall 
  each 
  year. 
  The 
  aver- 
  

   age 
  annual 
  volume 
  of 
  rainfall 
  throughout 
  twenty-three 
  years, 
  for 
  each 
  month 
  

   from 
  June 
  to 
  July 
  is 
  shown 
  in 
  fig. 
  2. 
  The 
  short 
  dry 
  period 
  of 
  each 
  wet 
  season 
  

   is 
  there 
  shown 
  to 
  be 
  marked. 
  In 
  fig. 
  3 
  the 
  average 
  monthly 
  and 
  annual 
  volume 
  

   of 
  rainfall, 
  for 
  every 
  month 
  to 
  the 
  present 
  year, 
  is 
  exhibited. 
  This 
  is 
  on 
  a 
  scale 
  

   of 
  inches 
  twice 
  that 
  of 
  fig. 
  2. 
  In 
  this 
  the 
  break 
  in 
  the 
  wet 
  season 
  of 
  most 
  of 
  

   the 
  years 
  is 
  plainly 
  marked, 
  but 
  it 
  does 
  not 
  occur 
  with 
  any 
  regularity 
  as 
  to 
  

   time.] 
  

  

  To 
  arrive 
  at 
  a 
  law 
  of 
  periodicity 
  in 
  atmospherical 
  phenomena, 
  will 
  demand 
  a 
  

   comprehensive 
  scheme 
  of 
  observations 
  over 
  a 
  large 
  extent 
  of 
  the 
  earth 
  and 
  ocean; 
  

   this 
  scheme 
  to 
  involve 
  all 
  the 
  conditions 
  of 
  atmospherical 
  variations, 
  and 
  the 
  

   local 
  relations 
  of 
  each 
  station 
  to 
  the 
  whole, 
  and 
  be 
  represented 
  in 
  graphical, 
  

   rather 
  than 
  in 
  numerical 
  order. 
  

  

  I 
  believe 
  in 
  the 
  law 
  of 
  periodicity 
  of 
  these 
  phenomena, 
  but 
  it 
  will 
  be 
  found 
  

   an 
  intricate 
  problem, 
  and 
  is 
  doubtless 
  involved 
  with 
  such 
  conditions 
  as 
  the 
  lunar 
  

   cycle 
  of 
  nineteen 
  years, 
  etc. 
  As 
  stated 
  in 
  my 
  paper 
  last 
  year, 
  upon 
  " 
  Suggestion 
  

   of 
  a 
  Cosmical 
  Cause 
  for 
  the 
  great 
  Climatic 
  Changes 
  upon 
  the 
  Earth," 
  we 
  must 
  

   expect 
  abnormal 
  exhibitions 
  of 
  these 
  phenomena 
  from 
  the 
  irregular 
  exhibition 
  

   of 
  the 
  materials 
  burning 
  upon 
  the 
  surface 
  of 
  the 
  sun 
  ; 
  but 
  in 
  a 
  prolonged 
  series 
  

   of 
  spectroscopic 
  observations 
  of 
  solar 
  phenomena, 
  and 
  observations 
  of 
  physical 
  

   phenomena 
  on 
  the 
  earth, 
  we 
  will 
  eventually 
  arrive 
  at 
  the 
  law 
  of 
  their 
  recur- 
  

   rence. 
  

  

  Dr. 
  George 
  Hewston 
  called 
  the 
  attention 
  of 
  the 
  Academy 
  to 
  a 
  new 
  

   species 
  of 
  Crustacean 
  which 
  had 
  recently 
  been 
  detected 
  in 
  the 
  bay, 
  

   and 
  which 
  was 
  exceedingly 
  destructive 
  to 
  wood- 
  work, 
  more 
  particu- 
  

   larly 
  the 
  piling 
  of 
  the 
  wharves 
  along 
  the 
  water 
  front 
  of 
  the 
  city 
  : 
  

   specimens 
  were 
  exhibited 
  under 
  the 
  microscope, 
  by 
  Dr. 
  Hewston, 
  

   who 
  referred 
  them 
  to 
  what 
  are 
  popularly 
  known 
  as 
  " 
  gribbles," 
  

   or 
  "Limnoria" 
  ; 
  and 
  to 
  which 
  he 
  attached 
  provisionally 
  the 
  name 
  

   of 
  Limnoria 
  California. 
  

  

  The 
  following 
  amendment 
  to 
  Sec. 
  2, 
  Art. 
  Ill 
  of 
  the 
  Constitution 
  

   having 
  been 
  presented 
  to 
  the 
  Trustees 
  as 
  required 
  by 
  Article 
  VII, 
  

   was 
  submitted 
  to 
  the 
  Academy 
  and 
  unanimously 
  adopted 
  : 
  

  

  