LXXX. 



NOTES ON HYDRAULIC BORING APPARATUS. 







No. 



Total Cost 



Locality. 



Strata Passed Through. 



OF 



Depth 



per 







Bores 



Bored. 



Foot. 



* Manning Eiver, Killa- ) 



For the most part through 



ft. 



s. d. 



warra and Bungay ( 



shale with a little sand 



13 



345 



5 



* Camden Haven 



Principally indurated sand 



77 



2035 



1 8£ 



* Moruya 



Sand, decomposed granite, 











etc. 



7 



152 



3 8£ 



* Camden 



Sand and gravel, with 











bands of stiff clay 



4 



207 



3 8J 



*Dunmore, Patterson Eiver 



Drift and clay 



5 



309 



2 7 



* Hinton, Patterson Eiver 



Alluvial, sand and drift ... 



4 



118 



3 1 



* Murwillumbah, Tweed i 



Sand, clay and drift, bands 









Eiver . . \ 



of soft rock 



10 



540 



3 



Blue's Pt., Sydney Harbour 



Mud, sand, clay, and ballast 



12 



184 



2 5 



Pyrmont Bridge, do. 



Mud, clay, and soft rock... 



32 



654 



2 Of 



Dawes Pt. do. 



Mud, sand, and soft rock 



93 



380 



2 10f 



Sydney to North Shore ) 

 Bridge ... \ 



Mud, sand, clay, and soft 









rock 



35 



1818 



2 0£ 



* Hydraulic pressure was not used on these works. 



On the last mentioned work a careful record was kept of the 

 progress of the work and from it the following information has 

 been compiled : — 



Boring through 1161 ft. sand and clay, and soft 

 sandstone by hydraulic pres- 



9d. per ft. 



do. 320 ft. stiff clay and soft sand- 



stone by boring tools only... 

 Drilling through 337 ft. soft and hard sandstone... 



3s. 4d. 

 5s. 3d. 



per ft. 

 per ft. 



Total drilling 

 and boring... 1818 ft. ... ... ... 2s. OJd. per f t. 



Under favourable circumstances the tubes have been sunk 

 through coarse sand or mud 30 feet in one hour, and through 

 stiff mud or soft clay from 10 to 15 feet in the same time. The 

 clay that cannot be pierced by the 4 in. boring tubes under 

 hydraulic pressure of 110 lbs. to the square inch is very stiff 

 indeed. At Funafuti a depth of 108 ft. of coarse Halimeda sand 

 and coral gravel was pierced in 22 hours, and from this time 3 

 hours may be deducted for repairs to faulty hose, etc., giving 19 

 hours of actual work. 



When the depth of water exceeds 80 ft., driving the tubes 

 has to be conducted with great care even in perfectly smooth 



