to investigate the Structure of a Coral Reef by Boring. 507 



no further. We worked all Thursday and Friday with the sand 

 pump, but with no success ; the bottom of the hole was surrounded 

 by quicksand containing boulders of coral, and as fast as the sand 

 was got out, so fast it flowed in and faster. The water pumped 

 down disappeared through the sand, boring and a fortiori reaming 

 was impossible, and the tubes could not be driven owing to the inter- 

 spersed boulders. Had the tubes been provided with steel driving 

 ends we might have forced them down ; as it was, the effect of driv- 

 ing them was simply to curl in the lower end. Had we been pro- 

 vided with 4-inch tubes we could have made a fresh start, and might 

 have descended another 30 or 40 feet, but even then ultimate success 

 would not have been ensured, for the chance of meeting again and 

 again with intermixed sand and coral remained always open, and 

 every such encounter would have required lining tubes of diminished 

 calibre. 



Baffled in all our endeavours, and no other part of the island offer- 

 ing more hopeful prospects of success, we had no alternative but to 

 abandon the undertaking, and on July 30 we were taken from the 

 island in the " Penguin," and returned to Fiji. On landing there we 

 had the mortification to learn that additional apparatus was then on 

 the way to Funafuti, our friends in Sydney having with great 

 generosity at once despatched machinery for driving in sand on re- 

 ceipt of a letter I had sent informing them of the failure of our first 

 borehole. We had had no reason to expect such spontaneous assist- 

 ance, and even had we been fortunate enough to have remained 011 

 the island till the machinery arrived, we should probably not have 

 accomplished the object we had in view, though we might possibly 

 have carried the borehole down to a depth of about 400 feet. 



A very free communication must have existed between the bore- 

 hole and the sea, for whenever a big roller broke upon the reef the 

 rods lifted, and after the lining had been withdrawn, water spurted 

 out of the borehole with the fall of every wave. The open nature of 

 the reef is further indicated by the fact that the sea water rises with 

 every tide to fill certain depressions, which occur in many places in 

 the middle of the island; as the tide ebbs this water flows away down 

 fissures, often so rapidly as to form little whirlpools. 



Wherever I have seen the reef growing it has always presented 

 itself as clumps or islets of coral and other organisms with inter- 

 spersed patches of sand, and the borings would seem to indicate that 

 it maintains this character for a very considerable depth and possibly 

 throughout. The structure of the reef appears indeed to be that of a 

 coarse " sponge " of coral with wide interstices, which may be either 

 empty or filled with sand. 



As regards the nature of this " sand," it is important to observe 

 that it does not consist of coral debris; this material and fragments 



