ox THE DIP OF THE UNDERGROUND PALEOZOIC EOCKS. iol 



stone had been planed off in order to its being marked with punches, pre- 

 vented its yielding a proper recognisable impression, owing probably to 

 adhesion between the two surfaces. The core was tlierefore detached and 

 drawn up. It came to the surface in several pieces, but, as the lines of 

 fracture extended below the bottom of the shallow groove which existed 

 when the punch mai'ks were made, it was evident that no fracture had 

 taken place before the rock was marked. 



It then remained, in the first place, to measure the angle between the 

 direction of dip and the diameter marked on the crown or tube; 

 secondly, to ascertain, by a compass placed beyond the influence of the 

 iron of the boring machinery, the angle between the direction of the fixed 

 pointers to which the marked diameters were set and the magnet meridian; 

 and, thirdly, to learn from an authentic source, the angle then obtaining 

 between the magnetic and the true meridian. By this process it was 

 easily determined that the direction of the dip of the Silurian Rock at 

 Ware, at a depth of 828 feet below the surface, and 31 feet below the top 

 of the stratum, is about one degree west of true south. This is a mean 

 between the angles derived from the two distinct experiments, the varia- 

 tion between them having been 1° 12'. The angle of dip is 41° from the 

 horizon, as was clearly shown by layers of fossils, along which the stone 

 easily fractured. 



At Turnford, the general arrangement of the boring apparatus was 

 much the same as at Ware, the oidy diffei-ence of any consequence being, 

 that the rods were connected up in 20 feet instead of in 30 feet lengths. 

 The means employed in determining the dii'ection of dip were somewhat 

 similar to those already described, but greater difficulty was encountered 

 in obtaining reliable results. The complete success that had attended the 

 experiments at Ware warranted the belief that there would not be the 

 same necessity for repetition as when the methods were first tried ; l)ut 

 at the same time it was recognised that every result must in some way be 

 corroborated before it could be accepted as correct. 



In the first instance, three cutters, for making vertical lines on the 

 outside of the core in the way I have already described, were used. The 

 precautions which had been successfully adopted to guard against the 

 angular motion of the marking tool in its descent and ascent were again 

 employed. But while the said tool was being lowered, an inconsiderate 

 handling of the apparatus by one of the workmen gave rise to the fear 

 that some slight disturbance of the true adjustment of that apparatus had 

 been thereby caused. The marker, on being raised to the surface, came 

 up, not, as had hitherto happened, in the same position as that from which 

 it went down, but showed a rotation of [^ of an inch at the circumference, 

 equal to an angle of 5° 50'. Considering the circumstances attending 

 the interference that had taken place during the lowering, it was con- 

 sidered a fair inference that the core had been marked with the tool 

 turned in the direction in which it came up, not in the position given to 

 it before it was sent down. 



An endeavour was then made to obtain a cast in wax cement in much 

 the same manner as at Ware, but this proved a failure owing to a piece 

 that had broken away from the top of the core having fallen against the 

 side of the hole, so that the tube carrying the wax could not be got down 

 over it. Although no information was to be looked for in this instance, 

 still, as a test of the accuracy of the operation, the rods were guided as 

 usual during tlieir ascent, and when they came up were found not to 



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