142 Noiices rcspeding New Books. 



scribed, the means that are necessary for effectuig, upon a large 

 scale, what is practised on a very small one, by miners when 

 they meet with similar obstacles. Indeed, were it not for the 

 means of secnrity that are resorted to on many occasions, mines 

 ■would inevitably be overwhelmed and lost. 



Notwithstanding we may encounter obstacles that may re- 

 tard the daily jirogress, it is with satisfaction we contemplate 

 that every step we take tends to the })erformanGe and ultimate 

 completion of the object; and if we consider that the body of 

 the Tunnel must exceed the length of Waterloo Bridge, it 

 must be admitted that, if, instead of two years, three were ne- 

 cessary to complete the undertaking, it would still prove to be 

 the most economical plan practicable for opening a land com- 

 munication across a navigable river. 



No notice is taken here of the mode of constructing the de- 

 scents or a}iproaches into the Tunnel ; because whatever form 

 or direction it may be found necessary to adopt, it is obvious 

 that no difficulties oppose themselves to the accomplishment of 

 that part of the work, the expense of which is however taken 

 into account in the estimate. 

 Nature of the Ground under the bed of the River at Rother- 



hithe, at a short distance below the place now proposed for 



opening a Roadway. 

 No. 



1. Stratum consisting of brown clay 



2. Loose gravel with a large (juantity of water 



3. Blue alluvial earth inclining to clay - 



4. Loam ______ 



5. Blue alluvial earth inclining to clay mixed 



with shells _-_--- 39 



6. Calcareous rock, in which are imbedded 



gravel stones, and so hard as to resist the 

 pick-axe, and to be broken only by wedges 7 6 



7. Light-coloured muddy shale, in \vhich are 



imbedded pjrites and calcareous stones - 4 6 



8. Green- sand, with grg,vel and a, little water - 6 



9. Green sand -_-_-- 84 



68 4 



XXX. Notices respccling New Books. 



, Rccenlli/ published. 

 'X'lIE IVth Volume, Part II. of the Memoirs of the Wer- 

 nerian Natuial History Society has just appeared, and 

 the following are its contents: 



Sketch ol'the Geognosy of Part of the Coast of Northum- 

 berland, 



