1884.] of the Bay of Bengal in 18«8. 115 



monsoon proper in Bengal, an atmospheric eddy, or cyclonic voi'tex, 

 formed in the north-west angle of the Bay. It passed through North 

 Orissa, Chutia Nagpore, and South Behar into North Behar, where it 

 broke up on the 20th of June. This disturbance drew large supplies 

 of vapour from the southerly current advancing into Bengal from the 

 Bay, which it discharged as rain in unusually large amounts over a 

 considerable portion of Central and North Behar, and thus occasioned 

 very heavy floods in the Gya, Behar, Patna, Durbhanga, and Mozufferpore 

 districts. 



The disappearance of this eddy or whirl was followed by a partial 

 break in the rains. The winds, although they continued to blow from 

 the normal directions over Bengal and in the south and centre of the Bay, 

 fell off in strength. The sky was less densely clouded, more especially in 

 Central Bengal and Behar. The air also was drier, and the rainfall much 

 smaller in amount and confined to local showers, which fell chiefly in the 

 neighbourhood of the hills in North and. East Bengal. Whilst this partial 

 break in the rains (which commenced on the 20th) held in Bengal, the 

 winds diminished in strength pari passu over the north of the Bay. They 

 were light to moderate, and rarely exceeded force 3. The weather was 

 comparatively fine, and the sea almost smooth. 



The wind observations taken at Nancowry and Port Blair show that 

 the south-westerly winds of the centre and south of the Bay, which had 

 been very feeble from the 15th, began to increase in force on the 23rd, and 

 blew strongly during the remainder of the month. This apparently 

 indicated the commencement of another burst of the monsoon. 



It appears to be a general rule that each strong advance of south- 

 west monsoon winds and consequent influx of aqueous vapour into Bengal 

 commences in the south of the Bay. The winds first strengthen for some 

 days in that part of the Bay, as is proved by the wind observations at the 

 Ceylon stations and at Nancowry in the Nicobars. The area of strong winds 

 then extends northwards. When the advancing strong winds approach the 

 Burmah and Bengal coasts, there is a strong tendency to eddjdng motion 

 at and near the front. This incipient vorticose motion may, under 

 favourable conditions, develop into a large cyclonic circulation and storm. 

 The strong current, in the present instance, advanced northwards along 

 the Burmese and Arrakan coasts, and increased the strength of the winds 

 at Diamond Island from the 25th, and at Akyab from the 26th. These may, 

 therefore, be assumed as the dates of the arrival of the front of the advanc- 

 ing mass of air in the latitudes of these two stations. The log of the Pcmba 

 proves that, on the 27th, the force of the winds off the west Burmese coast 

 was very considerable and averaged 9. At the same time that these strong 

 winds were blowing off the Burmese coast, the winds at the Head of the Bay 



