186 Memoranda regarding a Bormg, 8^c. [No. 3^^ 



ing of sea saiid and minute broken shells with a larger proportion of 

 black mud — small cylinder, which had not moved, only reaching to 

 42 feet, or 5 feet 3 inches short of the boring. 



Eleventh dav 48 Monday, ^tJi. — In the interval from Saturday night 

 feet 3 inches. Monday morning the large cylinders had sunk about 



2 feet, and in the course of deepening the pit between 7 and 10 

 A.M. a further sinking to the amount of 18 inches took place. 

 On sounding, it appeared that 5 feet 3 inches of soil had made 

 its way into the boring,* or up to the lower edge of the small cylin- 

 der since Saturday night. On using the water cylinder the whole 

 of this accumulation was removed in little more than an hour, 

 and at 11 a. m. (depth 48 feet 3 inches) it appeared that 6 feet 



3 inches had been gained in 1 hour 45 minutes, further pro- 

 gress was now prevented by the surface soil having fallen in at 

 the top in consequence of the sinking of the upper cylinder. The 

 black mud above alluded to, which seems to merit particular at- 

 tention, commences to make its appearance at about a depth of 35 

 feet, and although at this point its amount is small in comparison 

 with the sand with which it is mixed up, still it appeared to modify 

 to some extent the advance of the cylinders, at a depth of 42 feet 

 the soil had become extremely dark coloured, and here for the first 

 time since the commencement of the boring we were able to make a 

 considerable advance with the borer (to the amount of 6 feet) beyond 

 the end of the cylinder, the tenacity of the soil being such as to 

 arrest its further progress. The auger employed during the latter 

 part of the boring, although smaller than that used at its commence- 

 ment, could with difficulty be screwed into a depth of 10 inches, 

 showing that in its natural or compressed state the soil was well cal- 

 culated to withstand pressure or other imposed force. 



From a rough examination of the mud at the depth of 47 feet, it 

 appeared to consist of 20 per cent, of sea sand, the remainder being 

 made up of Aluminum, Carbonate of Lime and Humus, but the me- 

 chanical qualities of the soil rather than its chemical composition 

 being the object of inquiry, no more accurate analysis has been 

 thought necessary. 



* This breaking down or infiltration of the soil into so large an aperture is a result 

 which might naturally be expected to OCCur under the circurastaaces in any alluvial soil 

 however stiff its compositiou. ^ 



