358 CLIMATE. 



Group are much about the same, viz., about 150 inches : the chief 

 difference between the two regions being, that in the former region, 

 there are a greater number of rainy clays and fewer heavy falls. 

 The heavy falls, when they do occur, are not easily forgotten ; thus, 

 at Treasury we measured, in July, 1884, 11 inches of rain in 10 

 successive hours ; but the daily record was only 8'09 inches, since 

 the rain began in the evening of one day and lasted well into the 

 following mornino-. 



During the heavy rainfalls in these regions the streams swell in 

 an astonishingly quick manner. Rivulets become turbid streams, 

 the whole hill-slope discharges a continuous sheet of water, and the 

 water rushes down the permanent stream-courses with the roar of a 

 mountain-torrent. Large blocks o£ stone are swept some distance 

 along the lower courses of the streams ; and the trunks of trees 

 are carried by each successive flood further and farther towards the 

 mouth of the stream. 



It should be now remarked that the averao^e rainfall for the 

 year, Avhich I have estimated from observations made in different 

 parts of the Solomon Group at about 150 inches, only applies to 

 the coast. It is probable that this estimate is generally applicable 

 to the coasts of these islands, except on the lee sides of the loftier 

 islands.^ 



This brings me to the question of the rainfall in the higher 

 regions. The rainfall will increase with elevation until a certain 

 height is reached, where the clouds attain their maximum density ; 

 at such a level the greatest rainfall will occur. I learn from an in- 

 teresting paper by Mr. Bateman on this subject,^ that it may be 

 inferred that in the Lake District of England the greatest rainfall 

 occurs at an elevation of 2,000 feet, which is the level of maximum 

 cloud density. In India, an elevation of 4,500 feet represents the 

 level at which the gi-eatest rainfall occurs. In the Solomon Islands, 

 a greater height will have to be attained before the level of maxi- 

 mum cloud density or that of the greatest rainfall will be attained. 

 Probably I shall not greatly err if I assume it to be between 5,000 

 and C,000 feet. I have aheady observed that the south-east trade, 

 subject to its usual vai-i^tions, is the prevailing wind in the eastern 

 part of the group for nearly two-thirds of the year. Coming laden 

 with its watery burden, it first strikes the eastern slopes of St. 



^ By the lee sides, I mean those sheltered from the prevaiUng S.E. trade. 

 " Jourtfal of the Victoria Institute. Vol. XV. No. 59. 



