﻿70 
  EEPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  erdmagDetiscben 
  VariatioiieD, 
  von 
  E. 
  Kluge. 
  Leipzig^ 
  18C3. 
  102 
  pp., 
  

   1 
  pi., 
  8vo.) 
  

  

  Whether 
  any 
  one 
  has 
  previously 
  taken 
  up 
  the 
  question 
  in 
  its 
  entirety 
  

   I 
  cannot 
  say. 
  (The 
  lunar 
  disturbance 
  of 
  gravity 
  that 
  excited 
  attention 
  at 
  

   a 
  recent 
  meeting 
  of 
  the 
  British 
  Association 
  doesnot 
  influence 
  the 
  prima 
  

   facie 
  case. 
  H. 
  E. 
  H. 
  Darwin, 
  Rep., 
  1881). 
  Councillor 
  Schwabe, 
  of 
  Des- 
  

   sau, 
  was, 
  according 
  to 
  Humboldt, 
  the 
  first 
  to 
  tabulate 
  numerically 
  the 
  

   solar 
  spots, 
  and 
  his 
  tables, 
  published 
  originally 
  in 
  Scnumacher's 
  Astro- 
  

   nomische 
  Nachrichten, 
  No. 
  495 
  (Bd. 
  XXI, 
  1844), 
  p. 
  235, 
  and 
  afterw^ards 
  

   more 
  fully 
  given 
  in 
  the 
  fourth 
  volume 
  of 
  Cosmos, 
  show 
  the 
  fluctuations 
  

   of 
  the 
  solar 
  photosphere 
  between 
  the 
  years 
  1820 
  and 
  1850, 
  from 
  actual 
  

   eye 
  observation. 
  Schwabe's 
  table 
  has 
  been 
  sub 
  equently 
  enlarged 
  by 
  

   other 
  workers. 
  Professor 
  Wolf 
  carrying 
  it 
  back 
  to 
  1750 
  and 
  forward 
  to 
  

   1860 
  and 
  1875, 
  and 
  pointing 
  the 
  maximum 
  of 
  spots 
  of 
  1828 
  in 
  Schwabe's 
  

   table 
  as 
  1829. 
  The 
  axiom 
  I 
  have 
  employed 
  in 
  carrying 
  the 
  sun-spot 
  

   cycles 
  farther 
  into 
  the 
  past, 
  will 
  be 
  seen 
  then 
  to 
  be 
  justified 
  by 
  a 
  refer- 
  

   ence 
  to 
  M. 
  Poey's 
  table 
  of 
  earthquakes 
  and 
  volcanic 
  eruptions 
  in 
  the 
  

   Brazils, 
  in 
  the 
  Comi)tes 
  Eendus, 
  already 
  alluded 
  to; 
  it 
  assumes 
  that 
  the 
  

   great 
  periods 
  of 
  earthquake-commotion 
  and 
  volcanic 
  activity 
  harmon- 
  

   ize 
  with 
  the 
  maxima 
  and 
  also 
  with 
  tlie 
  minima 
  periods 
  of 
  solar 
  spots; 
  

   and 
  on 
  this 
  assumption 
  I 
  have 
  consulted 
  various 
  seismic 
  tables 
  and 
  

   checked 
  off 
  the 
  periods 
  of 
  disturbance 
  by 
  the 
  records 
  which 
  in 
  their 
  

   copiousness 
  or 
  defect 
  fully 
  indicate 
  the 
  required 
  discontinuity 
  recurring 
  

   at 
  stated 
  intervals. 
  But 
  when 
  these 
  periods 
  were 
  found 
  it 
  further 
  be- 
  

   came 
  very 
  evident 
  to 
  me 
  that 
  it 
  was 
  necessary 
  to 
  adopt 
  some 
  method 
  

   of 
  numerical 
  precision 
  in 
  order 
  to 
  eliminate 
  the 
  years 
  of 
  the 
  sun-spot 
  

   cycles. 
  To 
  this 
  intent, 
  therefore, 
  I 
  first 
  drew 
  up 
  the 
  mean 
  periods 
  of 
  

   greatest 
  commotion 
  in 
  Europe, 
  Asia, 
  and 
  America, 
  and 
  placed 
  the 
  max- 
  

   ima 
  and 
  minima 
  of 
  sun-spots 
  given 
  in 
  Wolf's 
  table 
  into 
  the 
  breaks, 
  

   where 
  they 
  fell 
  in 
  order, 
  I 
  think 
  I 
  may 
  say, 
  at 
  first 
  sight. 
  I 
  then 
  took 
  

   out 
  the 
  latter 
  extreme 
  year 
  and 
  the 
  mean 
  year 
  for 
  the 
  minima 
  years, 
  

   and 
  the 
  former 
  extreme 
  year 
  and 
  the 
  mean 
  year 
  for 
  the 
  maxima 
  years. 
  

   One 
  or 
  other 
  of 
  the 
  numbers, 
  which 
  themselves 
  rarel}^ 
  differed 
  by 
  more 
  

   than 
  a 
  year, 
  should 
  give 
  me 
  as 
  I 
  found 
  the 
  epochs 
  of 
  fewest 
  or 
  most 
  

   spots 
  required. 
  

  

  To 
  explain 
  more 
  fully, 
  let 
  us 
  examine 
  the 
  list 
  of 
  earthquakes 
  and 
  

   volcanic 
  eruptions 
  for 
  any 
  breaks 
  in 
  the 
  violence 
  and 
  extent 
  of 
  the 
  dis- 
  

   turbances 
  and 
  mark 
  the 
  periods 
  obtained 
  in 
  this 
  manner, 
  thus 
  (1839- 
  

   1838). 
  We 
  will 
  then 
  arrange 
  these 
  periods 
  of 
  activity 
  taken 
  out 
  from 
  

   many 
  tables, 
  thus: 
  

  

  