48 PROFESSOR T. W. EDGE WORTH DAVID. 



fresh site. He himself at the time was very ill with a dangerously ulcerated leg ; two 

 of the other drill men were also suffering from ulcers though less severely. It looked 

 as though our attempts at boring the atoll would prove a failure. It was now over 

 three weeks since we had landed on the island, and we had bored only to a depth of 

 62 feet. At this juncture, Foreman Burns came to the rescue and begged to be allowed a 

 little longer trial at recovering the under-reamer. On July 16th, amid great shouting 

 and cheerino-, the broken under-reamer was brought to the surface, and the work of 

 lining the bore with 5-inch tubes was at once proceeded with. The coral rock proving 

 somewhat soft below this level, it was found possible to "monkey" down these 

 5-inch pipes to the depth of 118 feet. At this depth the 5-inch pipes lining the bore- 

 hole screwed on to their lower end, telescoped into the steel shoe, and it became 

 necessary to cut away the telescoped portion with a steel cutter.* 



Fortunately Ave had a duplicate set of left-handed screw rods for tliis work. 

 Otherwise the result of the boring with the steel cutter Avould have had the effect of 

 unscrewing the steel shoe, which would have proved fatal to further boring. It was 

 of course impossible to drive down the 5-inch casing any deeper, after the bottom 

 tube had telescoped, so that it at once became necessar}'' to reduce the diameter of the 

 bore. Tliis was a misfortune of no little ffravitv. It meant that we had now come to 

 our last resource, the 4-inch lining pipes. If any accident should liappen to them we 

 could go no fartlier. Great precautions were accordingly taken in preparing for using 

 our last set of lining pipes. The steel shoe was found to have been a trifle over- 

 tempered, and so it was re-tempered very carefully at the forge until by actual 

 experiment it was ascertained exactly what temper suited it l)est for cutting coral 

 rock without risk of splintering on the one hand or bending on the other. This having 

 been done, the greatest attention was paid to securing an accurate, close fitting and 

 rectangular joint wliere the lower rim and the soft steel lining pipe rested, when 

 screwed home, upon the shoulder of the hard steel shoe. Our previous accident had 

 taught us the vital importance of attention to these details. 



I)o:e so constructed that the}' jet water from the very l^ottom was specially enijjhasised in this case. In 

 the screw tap, h}' means of which the Imiken half of the under-reamer was eventually lecovered, the 

 escapes for the hydiaulic water had been drilled .about 4 inches above the bottom of the tap, and j'ct 

 although the jets wei'e so near the bottom, it was found impossible even with several tons pressure to force 

 the lower part of the tap through the silt so as to admit of the threads at the upper end of the tap 

 gripping the under-reamer. The tap had actually to have the lower 4 inches cut t)ff it, at oui' portable 

 forge, before it could be diiven through the silt.' As soon as this was done, so that the water was 

 jetted from the actual bottom of the tap, not the least difficulty was experienced in driving it through the 

 silt, and getting it to enter the cavitj' at the top of the broken under-reamer. 



* This mishap was due to the fact that the bearing surface of the bottom of the pipe against the 

 shoulder of the steel shoe was not accurately at light angles to the axis of the boring pipe, but instead 

 had a very slight inclination inwards. The result of this was that when the heavy monkeying bulged 

 the threads at the screw joint slightly downwards, the lower rim of the pipe commenced to telescope into 

 the collar of the steel shoe. 



