I 



May 3, 1877] 



NA TURE 



\ 



For a time the quantity of water thus obtained, as at 

 Merton, Garrett, and many other points, seem to have 

 induced the belief that an inexhaustible source of the all- 

 essential element had been discovered ; but the rapid 

 multiplication of these Artesian wells soon revealed the 

 fact that the new and valuable stores had their limit, and 

 that this limit was being very rapidly approached in con- 

 sequence of the excessive demands which were now being 

 made upon the new source of supply. The deepening of 

 the wells, by which means water was drawn from the 

 Chalk, as well as from the Tertiary strata, promised, how- 

 ever, to do something towards staving off the evil day 

 when London would no longer be able to depend on 

 drafts being honoured by her great subterranean bank. 



Such was the state of the question when Mr. Prestwich, 

 now the Professor of Geology in the University of Oxford, 

 undertook its complete investigation as an important 

 geological problem. No one more competent for the 

 task could possibly have been found, for during many 

 years Mr. Prestwich's studies had been devoted to the 

 Tertiary deposits of the London and Hampshire basins ; 

 and his great work — " A Geological Inquiry respecting the 

 Water-bearing Strata of the country around London, with 

 Reference especially to the Water-supply of the Metro- 

 polis," which was published in 1851 — is a masterpiece of 

 minute observation and close and accurate reasoning. 



More than this, the geologist points to the work with 

 pardonable pride, as affording convincing proof that his 

 science has now acquired a character for exactness, analo- 

 gous to that which is justly regarded as the crowning 

 attribute of astronomy. After a most elaborate study of 

 the nature and relations of the various strata which crop 

 out all round the London Basin and of the disturbances 

 to which they have been subjected since their deposition, 

 Mr. Prestwich ventured on a bold p)cdictio)!, namely, 

 that the Chalk beneath London would be found to have a 

 thickness of 650 feet, the Upper Greensand of 40 feet, 

 and the Gault of 150 feet. (Op. cit. p. 142.) 



At the time when this announcement was made no well 

 in London had been sunk to a greater depth than 300 feet 

 in the Chalk, but now we can appeal to no less than four 

 deep borings in the metropolis, which afford the most 

 convincing proof of the reliability of the data, and the accu- 

 racy of the reasoning by which Mr. Prestwich arrived at 

 his interesting results. For the sake of distinctness, we 

 place the estimated and determined results side by side 

 in a tabular form : — 



M r. Prestwich's Estimate. 



Boring at 

 Kentish 

 Town. 



Chalk 650 



Upjjcr Gieensand 40 

 Gault 150 



645 

 1 1^ 



646 

 12 

 148 



050 

 40 

 (?) 



iJoi'iDg at 

 Meux's 

 Brewery. 



653 

 28 



159 



called " Lower Greensand," would in the future afford a 

 most valuable underground source of water-supply to our 

 overgrown city. 



But in 1855 Mr. Godwin-Austen brought before the 

 Geological Society of London his masterly essay " On 

 the Possible Extension of the Coal-Measures beneath 

 the South-Eastern Part of England," in which he an- 

 nounced the conclusion — based on a most elaborate study 

 of the geological structure of the South of England and 

 the adjoining portions of the Continent of Europe — that 

 an old ridge of Palxozoic rocks underlies the line of the 

 Thames Valley, and is only concealed from us by the 

 Upper Cretaceous strata. 



Mr. Godwin-Austen's announcement was as strikingly 

 verified as was that of Mr. Prestwich ; for, in the same 

 year that it was made, a boring at Kentish Town which 

 passed through the Gault, reached a curious series of red 

 rocks which are now believed by geologists to be either a 

 portion of the old Pateozoic ridge itself, or a set of litto- 

 ral deposits formed upon its flanks. And in 1857 the 

 deep boring at Harwich afforded still more unmistakable 

 evidence of the existence of this old Pateozoic ridge in 

 the fact that black slaty rocks were found immediately 

 below the Gault clay. 



Although the old ridge of Pakeozoic rocks must thus 

 limit the area of the available water-bearing "Lower 

 Greensand " beneath the metropolitan district, yet Prof. 

 Prestwich has constantly argued that very large and 

 valuable supplies of water will yet in all probability be 

 obtained from the latter source. 



Hence it is that the endeavour to tap this great subter- 

 ranean reservoir, which is now being carried out in such 

 an enterprising spirit by the Messrs. Meux and Co., in 

 the Tottenham Court Road, is attracting so much atten- 

 tion from geologists and engineers. The nodular beds at 

 the base of the Gault were reached at a depth of 999 feet 

 from the surface, and some sixty feet of rock below has 

 since been penetrated. The splendid cores brought up 

 by the diamond-borer are at once submitted to Mr. 

 Robert Etheridge, the palaeontologist of the Geological 

 .Survey, who is carefully studying every trace of fossils 

 which they exhibit. At present there are very strong 

 grounds for believing that the " Lower Greensand " has 

 been reached, and we soon hope to be able to announce 

 that the new source of water supply, so long ago pointed 

 out by Prof. Prestwich, has at last been made available 

 for the ever-increasing necessities of this great city. 



J. W. JUDD 



When it is remembered that the Chalk graduates down- 

 wards insensibly into the Upper Greensand, and that 

 it is almost impossible to decide on their line of sepa- 

 ration in the cores brought up by boring operations, it will 

 be admitted on all hands that the agreement between the 

 estimated and proved results is marvellously close. 



One of the most important conclusions of Mr. Prest- 

 wich's work was that the strata below the Gault, the so- 



LATHAM'S ENGLISH DICTIONARY 

 A Dictionary of tlic. English Langnos^c. Abridged by 

 the Editor from that of Dr. Samuel Johnson, as Edited 

 by Robert Gordon Latham, M.A., M.D.,&c. (London : 

 Longmans and Co., 1876.) 



WE consider ourselves justified in reviewing an 

 English dictionary in these pages for two reasons ; 

 first, because the method of its construction ought to be 

 rigidly scientific, and second, because a large proportion 

 of the words in any modern English dictionary must 

 necessarily be scientific terms. 



It is admitted by all competent to pronounce an opinion 

 that there is ample room for a new dictionary of the 



