Notices respecting New Books. 311 



experiments in progress on electrolytic bismuth. We expect 

 then to be able to state the results obtained for specimens of 

 bismuth of known chemical purity, and to distinguish between 

 those effects which are due to physical condition and those, if 

 any, arising from the presence of minute traces of impurity. 



XXVI. Notices respecting New Books. 



A Geological Inquiry respecting the Water-bearing Strata of the 

 Country around London, with Reference especially to the Water- 

 supply of the Metropolis ; and including some Remarks on Springs. 

 By Joseph Prestwich, F.G.S. 8vo, ix & 238 pages. Gurney 

 and Jackson : London, 1851-1895. 



THIS useful work was first published in 1851, and is now 

 re-issued, for reasons given in the Preface, with some additions, 

 by the energetic author Dr. J. Prestwich, F.R.S., &c. &c, who has 

 greatly enlarged his experience in this and other branches of Geo- 

 logy during the long interval of forty years, occupied with active 

 research, including the work of his Professorship in the University 

 of Oxford. The large plate engraved in 1851 was accidentally 

 destroyed before a sufficient number of copies were printed for the 

 book ; and the remainder of the work was put aside, and the plate 

 not reproduced, because one of the sections of the plate (No. 1, from 

 Sussex to Bedfordshire) was proved to be incorrect, the palaeozoic 

 rocks having been discovered to be within reach under London. 

 It was thought, too, that this error affected the long section (No. 2 

 from Wilts to Essex) ; but these old underlying rocks are really 

 so much limited in area that the western portion of the district 

 traversed by the section is properly represented in it ; and the 

 inference as to the possibility ot a considerable supply of water 

 being obtainable from the Lower Greensand there still holds good. 

 For this reason the remainder of the printed matter of the book is 

 now issued, without the plate, but with a few new pages (pp. v 

 to ix). 



There is now proved to be a belt, variable in width, of water- 

 carrying Lower Greensand encircling the area of underground 

 palaeozoic rocks, over which borings do not give so large a water- 

 supply as the Lower Greensand can give. These sand beds extend 

 under the Chalk and Tertiary strata and beyond their outcrop ; 

 thus receiving the necessary rainfall. Their exact yield of water, 

 however, has not been yet ascertained. A certain amount has been 

 obtained by boring in the Lower Greensand, eastward of London, 

 at Shoreham, Strood, Prindsbury, and Loughton. In the western 

 division of the London Basin the recent boring at Wingfield, not 

 far from Ascot, affords ample proof that there exists a large under- 

 ground supply, as indicated by nearly 3000 gallons in the 24 hours, 



