Die.  2,  1895.]  THE  TROPICAL  AGRICULTURIST.  42? 
$oiirospond6no0. 
To  the  Editor. 
PKUFESSOlt  ARCHIBALD  ON  THE  MON- 
SOONS AND  THE  “ELEVEN  YEARS’ 
CYCLE.” 
Nov.  19. 
SiH, — As  I happen  to  be  again  passing  through 
this  earthly  Paradise  and  may  not  have  another 
opportunity  of  following  up  the  question  in  situ  I 
shall  be  glad  if  you  will  allow  me  a little  space  to 
refer  to  the  “eleven  year”  cycle  of  the  dates  of 
arrival  of  the  big  monssoon  at  Colombo  which  I 
placed  before  your  readers  in  1893  and  to  advert 
to  its  apparent  and  exceptional  failure  during  1893, 
■1,  and  5.  From  the  averages  for  the  cycle  from  the 
past  dates  since  18.')1  given  in  the  list  furnished  by 
the  Master  Attendant,  the  arrival  of  the  big  monsoon 
ought  to  have  been  2,  10  and  4 days  early  in 
1893,  1894  and  1895  respectively,  whereas  it 
Wiis  19,  18  and  30  days  late — differences  not 
onl}'  exceptionally  large,  but  entirely  opposite  to 
those  which  occurred  in  the  corresponding  indi- 
vidual nine  years  of  three  preceding  cycles  covering 
a period  of  thirty  years. 
Of  course  the  popular  verdict  will  be  that  the 
theory  has  failed,  and  so  I frankly  admit  that  it  has 
in  these  three  years  ; but  it  would  certainly  be  hasty 
to  infer  either  that  its  existence  is  mythical  or  that 
it  may  not  turn  out  to  have  a practical  as  well  as 
scientific  value  in  the  future  and  I venture  to  put 
forward  ray  reasons  in  support  of  this  claim. 
In  the  first  place  it  was  discovered  by  the  remark- 
able unison  that  was  found  to  be  displayed  by  the 
arrival  dates  at  Colombo  and  the  yearly  rainfall 
anomalies  of  the  Carnatic,  the  cases  in  which  early 
dates  at  Colombo  and  heavy  rainfalls  in  the  Carnatic 
and  late  arrivals  and  light  rainfalls  agreed,  being 
no  less  than  eighteen  out  of  22  with  only  one  dis- 
tinctly negative  case.  Such  a parallelism  itself  argues 
the  presence  of  law  and  even  granting  that  three 
cases  in  which  the  parallelism  fails,  have  now  to 
be  added,  they  only  make  the  ratio  of  favourable  to 
unfavourable  eighteen  to  four  instead  of  eighteen  to 
one.  Moreover,  since  the  concurrent  fluctuation  in 
the  Carnatic  rainfall  and  the  sunspots  has  been 
maintained  all  through,  notably  in  the  present  year 
as  referred  to  in  the  Pioneer  of  Nov.  5th,  the  ex- 
ceptional feature  seems  to  lie  entirely  with  the  Cey- 
lon dates  of  arrival. 
Now  as  the  Master  Attendant  may  be  assumed  to 
have  only  a small  personal  equation,  w'e  must  evi- 
dently look  either  to  some  local  pecularity  or  to 
some  general  cause  which  without  sensibly  altering 
the  supply  of  rain  to  the  Carnatic  or  Ceylon  has  exer- 
cised some  peculiar  effect  upon  the  conventional  date 
of  the  arrival  of  the  big  monsoon  at  Colombo. 
It  is  cei’tainly  a fact  which  has  been  officially 
admitted  by  Mr.  Eliot,  the  head  of  the  Meteoro- 
logical Service  of  India,  with  whom  1 have  been 
working  during  tlie  past  two  years,  that  ever  since 
the  beginning  of  1893,  some  extraordinary  and 
abnormal  set  of  conditions  has  prevailed,  not  only 
over  India,  but  over  the  entire  Indian  ocean,  as  far 
ns  data  are  available.  The  monsoons  of  1893  and 
1894  wore  abnormal  in  respect  both  of  cjuantity  and 
distribution,  and  it  was  only  the  other  day  as  ho 
was  leaving  for  a tour  of  inspection  in  Persia 
that  Mr.  I'lliot  asked  me  to  investigate  the 
possibility  of  these  conditions  being  coiurected 
in  some  way  with  an  unusual  quantity  of 
floating  ice  in  the  Southern  Ocean,  of  whose  pre- 
sence an  Orient  steamer  had  a vivid  proof  the  other 
day  by  receiving  70  tons  of  it  on  board  without  any 
manifest  after  colliding  with  a berg.  It  vvill  surely 
be  admitted  that  the  presence  of  such  a widespread 
abnormality  as  that  which  caused  the  monsoon  of 
1893  to  stand  out  in  contrast  with  all  its  prede- 
ceasors,  as  the  wettest  ever  knoivn,  and  that  of  1894 
as  the  second  wettest  in  India  may  be  allowed  to 
upset  temporarily  a law  which  depends  on  a regu- 
larly recurring  and  small  variation  of  sun-heat 
As  soon  as  these  abnormal  conditions  subside,  the 
normal  laws  may  be  expected  to  act,  and  the  cyclical 
law'  which  I firmly  believe  exists,  will  resume  its 
operations. 
Before  concluding,  I should  like  to  point  out  that 
the  rainfall  of  Ceylon  judging  from  Colombo  unlike 
that  of  the  Carnatic  does  not  seem  to  be  directly 
dependent  upon  the  early  or  late  advent  of  the  S.-W. 
monsoon  as  estimated  by  the  Port  officer. 
For  example  in  1893  when  it  was  19  days  late 
according  to  his  method,  the  rainfall  of  May  at  dolombo 
was  no  less  than  20'39  inches  or  nearly  double  its 
average  (11’34)  for  this  month  while  the  total  for 
the  year  was  2 inches  above  the  average.  Some 
people  would  be  inclined  to  fancy  such  a rainfall 
with  a S.-W  wind  would  of  itself  constitute  a mon- 
soon, but  I suppose  the  Port  officer  has  his  own 
opinion  about  what  constitutes  a biirst.  Again  in 
1872  when  the  burst  was  assumed  to  occur  on  May 
1st  which  was  18  days  earlier  than  usual  the  rain- 
fall of  May  was  1 inch  below  the  normal,  and  the 
total  for  the  year  25  inches  below  the  mean  for  25 
years,  and  nearly  the  lowest  on  record. 
It  would  almost  seem  therefore  from  these  instances 
that  an  early  arrival  of  the  big  monsoon  betokened 
a scant}'  rainfall  and  vice  versa.  1 have  therefore 
exanrined  this  point  w'ith  the  following  results. 
First  I have  taken  exceptional  years  and  then  all 
cases  of  early  and  late  arrivals.  The  results  are  given 
in  a tabular  form  below: — 
Table  I. — Extreme  monthly  falls,  arrival  of  big 
monsoon. 
inches 
Wettest  May  1888 
Driest  May  1882 
Wettest  November  1870 
Driest  November  1872 
28'78  one  day  early* 
2’62  normal  date. 
3l5'23  9 days  early. 
2'82  18  days  early. 
Table  II. —Big  monsoon  exceptional  arrivals. 
(1)  Early 
years  average 
rainfall  anomaly 
date 
May 
Oct. 
year 
1872) 
, May  (ith 
in. 
in. 
in. 
1874  1 
I (13  days 
0 
—1 
—8 
1883 
j'  early) 
1887  j 
(2)  Late 
187(1) 
, J une  5th 
in. 
in. 
in. 
1885  1 
(17  days 
-1-2 
-f  1 
—3 
1893  1 
r late) 
1894  J 
1 
Total  annual  fall  anomaly 
in. 
All  early  years  (11)  -i-O  S 
All  late  years  (12)  -t-2‘0 
Th  e balance  is  thus  in  favour  of  late  years  though 
the  amount  is  not  enough  to  be  practically  import- 
ant. The  general  result  appears  to  be  that  so  far  as 
Colombo  is  concerned  the  monthly  and  annual  falls  are 
not  directly  dependent  on  the  early  or  late  arrival 
of  the  soutli-west  monsoon,  l)ut  is  due  to  certain 
second.ary  and  probably  local  influences  which  mask 
any  regular  periodicity  ; but  that  in  general  the 
rainfall  at  Colombo  both  monthly  and  annual  is 
greatest  in  those  years  w’hen  the  arrival  of  the 
monsoon  according  to  the  port  officer’s  definition  is 
latest.  An  examination  of  the  rainfalls  at  other 
places  in  the  island  is  required  before  any  deductions 
can  be  drawn  for  districts  other  than  the  neigh- 
bourhood of  Colombo.  I hope  some  one  may  bo 
tempted  to  undertake  it  and  send  the  results  to 
the  Indian  Meteorological  Office,  which  is  studying 
the  general  conditions  that  affect  the  monsoons  of 
the  Indian  ocean. — I am  sir,  yours  faithfully, 
DOUGLAS  ARCHIBALD, 
Fellow  of  the  lioijal  Meteorological  Societg  of  London. 
* The  average  date  for  the  arrival  of  the  big  mon- 
soon is  taken  to  be  19th  May. 
