BEITISE ASS0CIA.TI01S" MEETING AT CAMBRIDGE. 



4G1 



tion,' No. 8, 1862, has mentioned some of these facts, but it seemed worth 

 while to throw them together in a distinct memorial, if only to draw atten- 

 tion to an enterprising and patiently-conducted operation of great extent, 

 by a single commercial firm, in obedience to geological principles. 



The wells (for there have been two attempts) arc situated at the foot of 

 Carrow and Bracondale Hill, Norwich, within a few yards of the river 

 Wensum, the object of the deep sinking being to obtain a water, for use 

 in the manufacture of starch, perfectly free from the impurities of that 

 found within the range of the chalk of the neighl)ou,hood. 



The operation chosen is that of boring by Messrs. Mather and Piatt's 

 machine. This machine consists of an iron boring-head, 8 or 10 feet in 

 length, armed with strong chisels, suspended by a flat rope wound round a 

 drum; the hammering or "jumping" motion being given by a special 

 steam piston. The neck of the borer is formed with a screw, on which a 

 collar connected with the flat rope works, the effect being that the borer is 

 gradually twisted when at work, so that the chisels constantly strike on 

 fresh points, and more thoroughly break up the materials met with. When 

 a sufficient quantity has been thus broken up, the boring-head is removed 

 and a " shell-pump" is let down having a valve at the base. On the pump 

 being set in action, the loose material is forced into the shell and brought 

 to the surface. In the hard chalk the rate of penetration accomplished 

 was 20 to 25 feet a day for 500 feet. 



The first well failed in consequence of the iron tubing employed to case 

 the bore slipping across and completely obstructing the action of the ma- 

 chine, at a depth of 775 feet. 



The second is being sunk a few yards off, on the same level as the first. 

 After a few feet of alluvium the borer passed through hard chalk, with 

 flints at distances of about G or 7 feet apart, for 700 feet, with the exception 

 of 10 feet at the depth of 500 feet, where the rock was soft, "like white 

 lead," and of a rusty colour. Thence the hard chalk continued, with 

 flints thicker together, viz. about 4 feet apart, to the depth of 1050 feet. 

 Then 102 feet were pierced, of chalk ./ree from Jlints, to the Upper Grreen- 

 sand, a stratum of about 6 feet, and next the gault for 36 feet : the whole 

 boring being full of water to within 16 feet of the surface. 



In this ganlt, however, the greatest obstacle has been met, and the com- 

 pletion of the work arrested for a considerable time past. This stratum is 

 soft, so that the chisels, effective in the harder upper strata, are of little 

 use. The material caves in from all sides as the instrument proceeds, and, 

 unfortunately, the rope has broken more than once, leaving the boring- 

 head below, and one now lying across the bore baffles the engineer's 



eflbrts to remove it. 



The strata passed through are — 



Feet. 



Alluvium 12 



Hard clialk, with flints . . . . 483"1 



Soft chalk 10 I 



Hard chalk, as before . . . . 190 j> 1042 

 Hard chalk, uitii flints, iu closer layers . 350 



Chalk, witliout Hints 102j 



Upper Grceasaud ..... 6 

 Gault, not yet passed through . . .30 



1198 



The fossils brought up have not been very numerous, as might be ex- 

 pected from the sniallness of the bore, viz. twenty-one inches in diameter. 



