G. H. HALLIGAN. 



LXXXI. 



water. If any movement of the boring punt takes place, owing 

 to the swell, variable current, or other causes, and a true blow 

 cannot be struck, its force is lost in the spring of the tube and 

 serious injury to the pipe is caused. This was particularly 

 noticeable when sinking the bores lately at the atoll of Funafuti 

 in 101 feet of water. The work was carried out by the author 

 from the bow of H.M.S. Porpoise, kindly lent by the Admiralty 

 for the purpose, but, although the water in the lagoon was as 

 smooth as it generally is in Port Jackson, the oscillation of the 



SECTIONS Of BORINCS 

 SUNK BY HYDRAULIC APPARATUS 

 —IN HEW SOUTH WALES 



-8JU- 



I 



& 



' *T 



t~~Z i@ 



mstz«*m 



Figs. 



7 AND 



ship prevented a true blow being delivered, when it became 

 necessary to drive the tubes, and the work could not be continued. 

 From a double punt, such as already described, where, of course, 

 no oscillation takes place, some heavy driving through stiff clay 

 and soft rock has been done in 80 feet of water. It is, however, 

 doubtful if the 4 in. tubes would stand much hammering in a 

 greater depth of water, however carefully done. 



The author wishes here to acknowledge his indebtedness to 

 Mr. H. Fleming, Resident Engineer Public Works Department, 

 to whose skill and constant care a large measure of the success 

 of the boring apparatus here described is due. 



