﻿Dr. 
  van 
  Rijckevorsel 
  on 
  the 
  Temperature 
  of 
  Europe. 
  463 
  

  

  I 
  think 
  also 
  that 
  these 
  curves 
  show 
  that 
  it 
  is 
  not 
  really 
  

   necessary 
  to 
  have 
  such 
  a 
  very 
  large 
  number 
  of 
  years 
  to 
  

   calculate 
  the 
  normal 
  temperatures 
  with 
  if 
  they 
  are 
  well 
  

   manipulated. 
  In 
  this 
  diagram, 
  for 
  instance, 
  the 
  curve 
  for 
  

   Konigsberg 
  is 
  the 
  result 
  of 
  46 
  years' 
  observations, 
  that 
  for 
  

   Catania 
  of 
  only 
  20 
  years 
  ; 
  and 
  you 
  will 
  see 
  that 
  the 
  result 
  is 
  

   quite 
  as 
  satisfactory. 
  I 
  have 
  even 
  got 
  curves 
  from 
  only 
  ten 
  

   years' 
  observations 
  which 
  show 
  exactly 
  the 
  same 
  peculiarities 
  

   as 
  others. 
  Of 
  course 
  a 
  larger 
  number 
  of 
  years 
  cannot 
  fail 
  to 
  

   make 
  the 
  normals 
  still 
  better. 
  Suppose 
  we 
  had 
  a 
  series 
  of 
  

   two 
  or 
  three 
  centuries, 
  it 
  is 
  very 
  probable 
  that 
  minor 
  ano- 
  

   malies 
  would 
  show 
  themselves 
  which 
  might 
  be 
  quite 
  as 
  real, 
  

   quite 
  as 
  permanent 
  as 
  the 
  larger 
  ones 
  I 
  am 
  able 
  to 
  point 
  

   out 
  now; 
  we 
  might 
  be 
  able 
  then 
  to 
  take 
  the 
  mean 
  values 
  

   directly 
  as 
  normal 
  temperatures 
  without 
  any 
  smoothing. 
  

   But 
  we 
  may 
  safely 
  predict 
  that 
  the 
  grosser 
  features 
  which 
  we 
  

   can 
  detect 
  now 
  would 
  in 
  no 
  way 
  be 
  altered. 
  

  

  What 
  I 
  have 
  just 
  said 
  is 
  also 
  proved 
  by 
  three 
  curves 
  for 
  

   the 
  Helder 
  which 
  I 
  have 
  drawn 
  *. 
  In 
  the 
  diagram 
  the 
  lower 
  

   curve 
  is 
  the 
  result 
  of 
  the 
  observations 
  of 
  the 
  25 
  years 
  from 
  

   1845-1869, 
  the 
  upper 
  one 
  of 
  the 
  next 
  25 
  years 
  from 
  1870-1894. 
  

   Now 
  this 
  series 
  is 
  not 
  a 
  homogeneous 
  one. 
  The 
  thermo- 
  

   meter 
  was 
  more 
  than 
  once 
  removed 
  from 
  one 
  place 
  to 
  another, 
  

   and 
  a 
  really 
  good 
  situation 
  seems 
  only 
  to 
  have 
  been 
  found 
  

   some 
  years 
  ago. 
  Also 
  the 
  mean 
  temperature 
  for 
  the 
  year 
  is 
  

   several 
  tenths 
  of 
  a 
  degree 
  higher 
  during 
  the 
  first 
  25 
  years 
  

   than 
  during 
  the 
  second 
  series. 
  Still 
  it 
  will 
  be 
  seen 
  that 
  the 
  

   two 
  curves 
  are 
  strikingly 
  similar. 
  In 
  June 
  and 
  July 
  there 
  is, 
  

   indeed, 
  a 
  difference. 
  It 
  is 
  evident 
  that 
  during 
  the 
  first 
  period 
  

   the 
  thermometer 
  cannot 
  have 
  been 
  quite 
  free 
  from 
  some 
  

   direct 
  influence 
  of 
  insolation. 
  But 
  even 
  here 
  you 
  will 
  

   remark 
  that 
  all 
  the 
  essential 
  features 
  appear 
  in 
  both 
  curves. 
  

   Only 
  in 
  the 
  lower 
  one 
  they 
  occur 
  earlier, 
  and 
  seem 
  a 
  little 
  

   distorted. 
  (Perhaps 
  this 
  might 
  even 
  be 
  a 
  means 
  to 
  detect 
  

   errors 
  in 
  the 
  location 
  of 
  the 
  thermometer.) 
  And 
  in 
  every 
  

   other 
  part 
  of 
  the 
  diagram 
  you 
  will 
  see 
  that 
  the 
  two 
  curves 
  are 
  

   nearly 
  absolutely 
  parallel. 
  This 
  shows 
  plainly, 
  I 
  think, 
  how 
  

   a 
  rather 
  short 
  series 
  of 
  observations, 
  how 
  even 
  observations 
  of 
  

   only 
  indifferent 
  quality, 
  can 
  be 
  made 
  use 
  of, 
  if 
  properly 
  

   handled. 
  

  

  The 
  middle 
  curve 
  shows 
  the 
  mean 
  of 
  the 
  two. 
  

  

  Again, 
  it 
  must 
  even 
  be 
  possible 
  to 
  give 
  normal 
  tempe- 
  

   ratures 
  for 
  any 
  place 
  in 
  Europe 
  a 
  priori, 
  with 
  not 
  much 
  more 
  

   than 
  a 
  very 
  approximate 
  knowledge 
  of 
  the 
  climate. 
  Suppose 
  

  

  * 
  This 
  diagram 
  is 
  not 
  reproduced 
  here 
  as 
  the 
  text 
  seems 
  sufficiently 
  

   clear 
  without 
  it. 
  

  

  