April  i,  1893.] 
617 
THE  TROPICAL  AGRICULTURIST. 
SEASONAL  FORECASTS  OF  WEATHER : 
THE  ADVENT  OF  THE  SOUTH-WEST 
MONSOON  IN  CEYLON  DEPENDENT 
ON  THE  SUN  SPOTS  CYCLE. 
Weather  prophets  all  the  world  over  have  found 
it  convenient  to  keep  up  the  popular  notion  that 
it  is  almost  impossible  to  forecast  the  weather  for 
more  than  a day  or  two  in  advanoe,  and  certainly 
so  far  as  England  and  other  extra-tropical  regions 
are  concerned  they  are  probably  acting  wisely  not  to 
attempt  anything  more.  Out  here,  however,  in  the 
sub-tropical  and  equatorial  zone  as  the  ancient 
Indian  elassios  have  it,  “the  sun  is  at  once  the 
agent  of  light,  the  principle  of  thought  and  the 
motor  of  all  things.”  And  whether  it  may  arise 
from  his  more  direct  rays  or  from  the  peouliar 
barrier  to  Arctic  influences  presented  by  the  range  of 
the  Himalaya,  the  Indian  area  is  peculiarly  charac- 
terised by  a series  of  constant  weather  conditions 
whioh  change  more  regularly  and  periodically  than 
those  of  any  other  region  of  the  world.  Even  the 
dates  on  whioh  the  two  great  monsoons  commence 
here  and  iD  India  lie  within  tolerably  well-defined 
limits,  and  the  weather  which  corresponds  can  be 
reckoned  on  with  respect  to  its  general  character 
in  ^different  parts  of  this  island  in  a manner  quite 
unknown  to  those  who  live  nearer  the  poles.  As 
our  readers  are  aware,  we  have  in  our  “ Handbook 
and  Directory”  on  the  authority  of  the  careful 
Master  Attendant  of  Colombo,  given  the  dates  of 
the  advent  of  the  little  and  big  monsoons  at 
Colombo  for  a long  series  of  years.  But  when  we 
come  to  analyse  the  apparently  regular  set  of 
conditions  governing  this  greatest  change  in  our 
seasonal  year — from  our  dry  hot  period  to  the 
refreehingly  cool  rainy  term — we  find  that  the 
South-West  monsoons  differ  a good  deal  in  them- 
selves and  in  their  arrival  in  different  years. 
Omitting  all  the  minor  inequalities  in  the  Weather 
from  day  to  day  incident  upon  the  actual  size  of 
rain  showers,  clouds,  strength  of  wind,  we  find  both 
the  dates  of  the  first  arrival  as  well  as  the  total 
amounts  of  rain  vary  in  different  years,  and  at  first 
sight  there  appears  to  be  no  law  regulating  such 
times  and  amounts.  Indeed  were  suoh  laws  as  a 
rule  plainly  visible,  meteorologists  would  long  ago 
have  raised  their  science  to  the  enviable  level  of 
accuraoy  and  honour  enjoyed  by  those  of  mathe- 
matics, astronomy,  and  physios.  If,  however,  any 
advance  towards  aoouracy  in  this  soienoe  is  ever  to 
be  attained  it  will  only  be  by  the  investigation  of 
these  longer  weather  periods.  For,  the  longer  the 
period  and  the  more  the  weather  conditions  are  re- 
garded with  reference  to  their  average  for  such  period 
and  not  simply  by  their  passing  oscillations,  the 
easier  will  be  their  correlation  with  slowly  changing 
physical  conditions  either  directly  or  indirectly  due 
to  astronomical  or  terrestrial  factors.  In  other 
words,  we  shall  find  it  easier  to  deal  with  seasonal 
ohaDges  than  with  those  of  merely  one  day’s  or 
one  week’s  duration. 
This  principle  whioh  is  well  recognised  in  other 
sciences  has  not  made  muoh  progress  yet  in  its 
application  to  meteorology;  but  it  may  be  within  the 
reoolleotion  of  some  of  our  older  residents  that  Ceylon 
colonists  were  among  the  fi  st  to  recognise  after  a 
praotioal  fashion,  the  existence  of  weather  cycles. 
The  late  Mr.  R.  B.  Tytler  was  among  the  first  to  name 
and  dwell  on  the  wet  and  dry  oyoles  in  Ceylon  with 
their  effect  on  the  coffee  crops,  especially  in  the 
drier  districts,  suoh  as  Dumbara,  Our  late  lamented 
senior  followed  up  the  hint  and  elaborated  from  the 
meteorological  records  available,  the  ten  to  twelve 
gears’  weather  ojole  whioh  attracted  the  attention 
I of  Mr.  J.  Norman  Lockyer  when  he-came  to  Ceylon 
with  his  Eclipse  Expedition  in  1881,  and  he  con- 
nected the  Ceylon  weather  with  the  sun  spot  cycle. 
Mr.  Lockyer  published  a paper  on  the  subjeot  in 
Nature  whioh  attracted  a good  deal  of  attention. 
About  the  same  time  or  soon  after,  Mr.  Meldrum  of 
Mauritius  published  elaborate  tables  establishing  the 
law  of  sunspots  and  rainfall.  Since  that  time,  the 
Indian  Meteorological  Service  which  is  recognised 
as  being  one  of  the  finest  in  the  world,  because 
it  has  been  administered  hitherto  by  trained  phy- 
sicists, have  given  much  attention  to  the  subject. 
Anglo-Indian  meteorologists,  attracted  no  doubt  by 
the  fascinating  nature  of  their  field,  have  been  among 
the  first  to  travel  out  of  the  orthodox  daily  fore, 
oast  and  attempt  to  give  some  notion  of  what  nature 
the  monsoon  is  l’kely  to  be  in  different  parts,  its 
probable  duration  and  intensity  as  regards  rain- 
fall, etc.  Obviously  anything  approaohing  Buooess 
in  suoh  a matter  would  be  of  immense  value  to 
agricultural  industry  throughout  India,  and  espe- 
cially to  the  rice-fsrmers  ; while  we  need  scarcely 
refer  to  its  interest  or  value  for  us  in  Ceylon.  To 
be  forewarned,  is  to  be  forearmed,  and  if  by  timely 
prescienoe  the  Government  of  India  could  avert  a 
possible  famine  by  sending  supplies  to  threatened 
districts,  we  should  all  feel  that  a service  which 
could  prove  itself  to  be  such  a useful  faotor  in  the 
social  economy  of  the  opposite  continent,  would 
deserve  to  rank  with  the  highest  administrative  and 
executive  departments  of  the  Government.  At  pre* 
sent  no  doubt  the  officers  of  the  Meteorological 
service  are  chary  of  predicting  too  certainly.  At 
the  outest  a certain  proportion  of  failures  may  be 
expected,  especially  if  the  predictions  are  made 
too  particular ; but  enough  has  already  been  dis* 
covered  to  show  that  a little  more  systematic 
disoussion  of  past  data  would  yield  valuable  results 
and  empirical  if  not  rational  laws  for  future  guidance. 
It  was  after  the  severe  famine  experienced  in 
Madras  in  1877,  that  tho  possible  reourrenoe  of 
drought  and  famine  in  periods  corresponding  with 
similar  periods  in  the  spotted  area  of  the  sun’s 
surface,  was  put  forward  by  Sir  W.  W.  Hunter 
and  Mr.  Lookyer.  A great  deal  of  attention  was 
naturally  attracted  to  what  was  perhaps  heralded 
at  the  time  with  too  great  a flourish  of  trumpets 
as  a solution  of  the  entire  problem-  And  yet  in 
spite  of  serious  divergences  from  a regular  law 
outside  certain  areas,  and  a fluctuation  too  small 
to  be  of  itself  enough  to  account  for  a dangerous 
drought  throughout  the  entire  province,  there  is 
no  doubt  that  sunspots  do  affeot  the  temperature 
and  other  weather  conditions  in  every  part  of  this 
earth.  Dr.  Meldrum  of  Mautitius,  Dr.  Hahn  of  Leip- 
zig, Prof.  Frith  ol  Zurioh  and  a host  more  have  shown 
how  the  influence  of  sunspots  ramifies  through 
everything  inoluded  under  the  head  of  weather. 
From  the  frequency  of  cyclones  in  the  Indian  Ooean 
to  the  length  of  glaoiers  in  Europe,  there  are  traces 
of  some  peouliar  influenoe  which  apparently  recurs 
periodically  about  every  eleven  years  with  the  sun- 
spots; and  though  up  to  the  present  sunspots  alono 
have  not  been  absolutely  employed  for  the  purpose 
of  forecasting,  the  investigations  whioh  have  been 
made  of  these  parallel  phenomena  have  yielded  inci- 
dentally other  results  of  considerable  value  to  soienoe. 
For  example  the  remarkable  period  in  the  winter 
rainfall  of  Northern  India  known  as  Messrs. 
Archibald  and  Hill’s  law—disoovered  by  the  late 
Professor  S.  A,  Hill  of  Allahabad  and  Mr.  Douglas 
Archibald,  formerly  Professor  in  the  Patna  College, 
Bengal,  — in  the  year  1876,  was  independently  dis- 
covered while  a comparison  was  bemg  made  be- 
tween the  oourse  of  the  rainfall  and  the  area  of 
sunspots.  It  will  be  inferred  from  the  above  that 
Mr,  Archibald  Douglas,  \yhg  was  here  the  Qthcr 
