130 SPOLIA ZEYLANICA. 



subject are difficult to co-ordinate. Drift bottle experiments 

 were first commenced by Hornell on Herdman's recommenda- 

 tion. These bottles were all liberated in unsuitable localities, 

 and frequently during transitory stages of the monsoon. The 

 results were therefore of little or no value. The fullest details 

 of all these drift bottle operations are contained in a ledger 

 handed over to the Ceylon Government by the Ceylon Com- 

 pany of Pearl Fishers durmg 1912. This ledger should be 

 accessible to Dr. Pearson. We found that during the south- 

 west monsoon there was an oceanic current running from west 

 to east in the vicinity of Ceylon. An account of the origin of 

 this current will be found in the " Challenger " publication — 

 The Science of the >S'ea— and a chart is given on pages 60 and 61 . 

 When we published our results we were unaware that this 

 current had ever been noticed before. During weak south- 

 west monsoons this current does not touch Ceylon, but runs to 

 the south and west. Under these conditions there is a surface 

 drift on the banks caused entirely by the wind, and this 

 drift runs to the north, both on the Ceylon and Indian sides. 

 This explains the difficulty quoted by Dr. Pearson on page 

 216, paragraph (6), although he himseK explains his own 

 difficulty on the same page. The same explanation was given 

 in our report (Part VI., page 236). 



Dr. Pearson states that (i.) we have not fully discussed the 

 causes which produced these currents ; (ii.) that we have not 

 realized that the drift experiments do not assist us to discri- 

 minate between oceanic current and ordinary surface drift ; 

 and (iii.) that in a weak south-west monsoon the northerly 

 current flowing along the Ceylon and Indian sides of the Gulf 

 of Mannar is probably only a surface drift. 



With reference to (i.), our Paper showed that we had to deal 

 with the inter-action of two phenomena : {a) an oceanic current 

 and (6) a surface drift , caused entirely by the wmd. A discussion 

 of (b) was given by us in detail. At the time we wrote the origin 

 of the oceanic current was unknown to us. That, however, 

 in no way affected the results. It is not necessary to know the 

 origin of wind before ascertaining that it blows, and that it 

 blows in a certain direction. But, as before stated, the origin of 

 this oceanic current is dealt with in other i)ublications. In 



