32 CONTRIBUTIONS TO THE ORNITHOLOGY OF INDIA. 



April are the driest months, and the highest humidity coincides 

 with the time of the south-west monsoon. The rainfall of Port 

 Blair amounts to 117-8 inches on the average of six years. 

 The monsoon rains set in, in the early part of May, occasionally 

 even in April, and last till the beginning of November. Heavy 

 showers are not infrequent in February, but March is always a 

 dry month, and January somewhat less so. While, therefore, the 

 total rainfall is only about half of that on the coast of Arrakan, 

 the monsoon rains begin somewhat earlier and end later at the 

 Andamans. On an average, rain falls on about 180 days in the 

 year. 



" On the Andamans, the annual variation of barometric pres- 

 sure, as compared with the mainland, is but small. At 61 feet 

 above sea level the mean pressure is 29*853 inches in December, 

 and 29*718 inches in June. The mean annual oscillation on the 

 averages of the months is, therefore, about 0*14, while in Madras 

 it amounts to 0'29 and at Akyab to 031 between January and 

 June. 



(i The Andamans are situated full in the course of the monsoon 

 currents of the Bay of Bengal. The change from the south- 

 west to the north-east monsoon takes place in October, in which 

 month the winds are, as a rule, more or less conflicting and 

 sometimes from S. E. But by the beginning of November 

 the N. E wind blows pretty steadily, and generally conti- 

 nues from that quarter up to the end of April. In May the 

 south-west monsoon sets in accompanied by heavy rain, and 

 prevails without intermission up to the end of September. 



" At the change of the monsoons, stormy weather is common 

 at the Andamans, as elsewhere in the bay ; and many of the 

 most severe cyclones, that visit the Indian and Burmese coasts, 

 originate in the neighbourhood of these islands and the Nico- 

 bars. But although thus situated near the cradle of these 

 storms, the records of the last few years do not show that they 

 have actually been traversed by any one of them. Those that 

 are formed to the westward travel to the west or north-west, 

 while those that are formed in the Andaman sea appear generally 

 to travel northward. 



" Judging from the evidence of a meteorolgical register kept at 

 Nancowry in the Nicobar Islands during the south-west monsoon 

 of the past year, and also from the general similarity of geographi- 

 cal conditions, that group would appear to enjoy a climate differ- 

 ing but little from that of the Andamans. During the period in 

 question, the average temperature was from 1° to 3° lower in 

 the Nicobars, (except in the month of July) while the humi- 



