CURRENTS. 235 



the gulf, for with its fluctuations in strength the whole trend of the flow of water in the entire gulf changes. 

 When the monsoon is ■weak this oceanic current is scarcely felt, and the south-west monsoon has full 

 play in the gulf, where the current then runs north. When the monsoon is strong and steady, this oceanic 

 current has an easterly course from points between Cape Coniorin and Tuticorm, and reacliing the Ceylon 

 coast about TaUaiviUu Point, turns, and runs south. 



These details have been repeatedly corroborated by commanders of local coasting steamers who 

 have had long experience. And dui-ing the south-west monsoon of 1910, 565 drift bottles were liberated 

 at various points in order to confirm the above facts. Of these 565 bottles, 291 were returned, giving a 

 percentage return of 51*5 per cent. In this connection it is important to note that with reference to 

 drift bottles liberated in otlier parts of the world the usual and average percentage return is one-tliird, 

 or 33 per cent., so that our experiment was very successful. 



The south-^vest monsoon usually commences in Jmie, and we started Hberating bottles at 

 definite stations at the end of June, 1910, and continued until September. The following is a summary 

 of the results. 



Drift bottles liberated off Cape Comoriu and off Colombo late in June, before the monsoon had 

 become severe, were recovered in the vicinity of Paumben, indicating a northerly current on both sides 

 of the gulf (viz., on the west side of Ceylon and the south-east side of Lidia). Early in July, as the 

 monsoon freshened, bottles liberated off Cape Comorin and Tuticorin took an easterly direction, and 

 were recovered along the Ceylon coast, from south of TaUaiviUu Point to GaUe, and even Dondra 

 Head, including Chilaw, Negombo, and Colombo. Bottles liberated off Colombo were also recovered 

 to the south. 



This result clearly indicates that the oceanic current in the fuU force of the monsoon runs east 

 to the Ceylon coast and then turns south, foUowing the contour of the land. The average rate of this 

 current was fomid to be 0- 5 knot per hour on its eastward course, and 1 knot when running south along 

 the Ceylon coast. The reason for the increase in the speed of the current wiU be dealt with later. 



It is significant that along the Ceylon coast south of TaUaiviUu Point the current runs in the 

 teeth of each prevailing monsoon. This current continued to flow untU nearly the end of July, during 

 which time the south-west monsoon blew strong and steady. At the end of July the monsoon moderated 

 and feU light, and the current was then observed to reverse and to run north again along the Ceylon 

 coast, and also along the Indian coast from Cape Comorin to Palk's Strait. During this lull, which 

 continued untU the middle of August, bottles liberated off ChUaw and TaUaiviUu Point on the Ceylon 

 coast were recovered north, at the head of the gulf, in the vicinity of Paumben and Adam's Bridge. 

 Those hberated off Cape Comorin, Tuticorin, and Manapad were also recovered at the same place. 



The monsoon strengthened again during the second week in August, and bottles hberated off Capo 

 Comorin and Tuticorin were again picjked up off the Ceylon coast as far south as Dondra Head. This 

 recurrence of the oceanic easterly current during strong south-west monsoon conditions was felt at 

 Tuticorin. The current continued steady up to the end of August, when the monsoon again began to 

 abate. During this third luU in the monsoon the current again took a northerly course, rumimg at a 

 rate of ■ 3 knot per hour ; and bottles liberated off Cape Comorin were agam recovered at Paumben, Delft 

 island, near Kayts, also at Point Calimere, 70 miles north of the Paumben Pass, and even at Tranquebar, 

 120 miles north of the Paumben Pass, both the latter points being on the Lidian coast. The explanation 

 of these apparently anomalous results, which admit of perfect co-ordination, is not merely interesting, 

 it is important. 



As we shaU shortly see, this oceanic current produces different effects on the Ceylon coast, for, 

 as already pointed out, on tlie banks not under lease and south of TaUaiviUu Point the oceanic current 

 runs south when the monsoon is strong, and when weak it rmis north with the \vind ; whUst on the area 

 under lease there is merely a surface drift dependent, as usual, on the wind. 



In now attempting to explain the irregularities of the oceanic current and the results relating 

 thereto, we would draw particular attention to the charts appended, without which it wiU be difficult 

 to foUow the text. 



