to investigate the Structure of a Coral Reef by Boring. 505 



work to sink trial pits on the line of tlie portage, one of these, 

 situated 70 feet from the high-water mark on the seaward face of 

 the reef, was sunk 12 feet through sand and blocks of coral, when 

 operations were brought a close owing to the influx of sea- water at 

 high tides. Two other pits were then commenced nearer the sea and 

 a little to one side (north) of the portage, at the margin of the solid 

 platform of rock, which extends down to the growing edge of the 

 reef and which is covered by the sea at high- water. These passed 

 through sand and fragments of coral. In the most northern of the 

 two pits the sand was somewhat consolidated, and so, proceeding a 

 few yards further north, as far in that direction as it would have 

 been possible to transport our machinery, we opened another pit, 

 which was sunk for a depth of 11 feet through fragments of coral, 

 crystalline coral limestone, and partly consolidated sand. The 

 bottom of the pit was 2 feet below the seaward margin of the reef, 

 and as we were not inconvenienced by an influx of sea-water and 

 Ayles was of opinion that the rock would " stand," we decided to 

 make our new venture at this spot. Taking into consideration the 

 difficulties of transporting our apparatus, I do not think a more 

 favourable locality could have been chosen ; it was close to the very 

 edge of the rocky platform, which is so hard that Darwin, speaking 

 of a similar platform in the case of another reef, says " I could with 

 difficulty and only by the aid of a chisel procure chips of rock from 

 its surface ;" and as near the sea as it was prudent or even possible 

 to go. Indeed, we had at first some doubt as to whether our pump- 

 ing pipes would ' : live " in the surf of the ocean margin, and feared 

 that the high- water spring tides might inundate the shaft ; our fears 

 in these respects, however, proved to be groundless. 



Tri&lpf /. 





Captain Field and myself were impressed with the need of addi- 

 tional boring apparatus, and he proposed that Ayles should go to 

 Sydney to see if it could be procured. I gave much anxious con- 

 sideration to this project, and discussed it with my colleagues, 

 Messrs. Hedley and Gardiner, and with Ayles. The information I 

 received from Ayles was not encouraging. He stated that we 

 should require a complete equipment of lining tubes from 10 inches 

 down to 21 inches in diameter, that 10-inch tubes were not to be had 

 in Sydney, and that even if we succeeded in obtaining all the 



