ON THE DIP OF THE UiNDERGROUND PALAEOZOIC UOCKS. 



445 



At neither place was there any Lower Green Sand, although in each 

 case the occurrence of a dark -coloured sand, several inches in depth, above 

 the Palseozoic Rocks gave rise to the belief that the stratum was repre- 

 sented in an attenuated form. Recent investigation by Mr. W. Whitaker 

 and Mr. A. J. Jukes-Browne has, however, shown that this was merely 

 the basement bed of the Gault, whilst the 64 feet of rock occurring 

 between the Gault and the Old Red Sandstone at Messrs. Meux's well, has 

 been declared by the same authorities to belong to the Jurassic system. 



I will now proceed to describe the various appliances, either suggested 

 or used, for obtaining the desired information, and the manner in which 

 the experiments were conducted. 



The first idea that occurred was, to make use of a magnetic needle. 

 Fig. 4. Fig. 5. 



- Rod for ^^~ ^^^^^ 



actiicUin^ stamper 



I VJizbuZar boring rod/ 



-nr 



Cor 



CcreCuJ/e, 



Stamper 



ouUzicitznff stamper 

 ■Tubular bonriff rod/ 



Core/ 



-Core Cab c 



\6iad£ 



\Stamper 



'jJiaprmdc n^eedle/ 

 \Waoo ceTTie/Ld 

 ^J)iapTcra^nt 



^Wa£C cement 



Scale, 1 iu. to 2 ft. 



Scale, 1 in. to 2 ft. 



Suitably mounted,?this would be lowered on to the top of a piece of core 

 that was still affixed to its base, and when it had come to rest in its 

 natural position, it would either be secured immovably to the core, or its 

 impress stamped in some way upon the top. If a sufficiently long piece 

 of core were then broken off and brought up, the angle between the line 

 of dip and the magnetic meridian of the day could be directly read off 

 the specimen by means of a protractor. For fixing the needle in position 

 when arrived at the bottom, various devices were suggested, including, 

 amongst others, its enclosure in a pressure-tight box, so arranged as to be 

 capable of becoming firmly attached to the core when lowered over it. In 



