204 CORAL AND ATOLLS 



Although this shght variation is clearly shown in the 

 table, it will be at once seen that the monsoon influence is not 

 marked ; there is nothing that could be entitled to the name of 

 " the change of the monsoon." 



The Trades blow a steady cool breeze day and night, and 

 they become another agent, and a potent one, in keeping up 

 that uniformity of conditions which is the outstanding feature 

 of the climate of the group. They give to the islands their 

 peculiar individuality, their sounds of rustling palm-leaves 

 and breaking surf, they give them their even temperature and 

 steady barometer; and more than this, they have impressed 

 themselves on the very formation and structure of the group 

 itself. 



The sky is seldom cloudless, partly of course for the 

 reason that so large an expanse of sky is always in view, but 

 partly too for the reason well known to sailors, that clouds as 

 a rule do mark the site of coral islands. Captain Maury, in his 

 " Sailing Directions," even goes further than this, and says : 

 " These cloud piles . . . are often seen to overhang the lowest 

 islet of the tropics, and even to stand above coral patches and 

 hidden reefs, ' a cloud by day ' to serve as a beacon to the 

 lonely mariner out there at sea." A lower stratum of large 

 fleecy cumuli moving steadily in the line of the Trades, and 

 an upper and very high stratum of thin long-drawn cirrus, 

 appearing by contrast almost stationary ; this is the most 

 ordinary sky picture, and will serve for the great majority of 

 days in the year. The upper stratum has, at times, a real 

 opposite movement to the lower, and whilst the cumulus 

 masses are drifting from the south and east, the overlying 

 cirrus comes from the north and west. This is well known to 

 the islanders, and is looked on, and rightly, as a sign of coming 

 rain. Although the northerly winds form such an incon- 

 spicuous constituent, when seen in the graphic representation 

 of the winds, still they are important winds for the islands, for 

 they bring the rain; they bring to-day, and doubtless have 

 brought in the past, new waifs and strays as tentative additions 

 to the fauna of the islands. After northerly winds, even of 



