206 



NATURE 



[August 17, 191 1 



PROBLEMS OF WATER SUPPLY. 

 The Geology of Water Supply. By Horace B. Wood- 

 ward, F.R.S. Pp. xii + 339. (London: Edward 

 Arnold, 1910.) Price 7s. 6d. net. 

 '"["'HE geology of water supply is one of those 



■*- applied subjects which are extremely difficult 

 to treat of adequately within the limits of a small 

 volume, inasmuch as geology constitutes only one of 

 the factors which have to be taken into consideration, 

 and the part which it plays varies with so great un- 

 certainty that each individual case must be dealt 

 with practically on its merits. It may be said at 

 once, however, that we have here an extremely useful 

 book, one which sets forth with great clearness the 

 main geological features to be recognised by the 

 engineer, chemist, or physical geographer when con- 

 fronted with a problem of water supply, and indicates 

 to him the critical point where the geological doctor 

 must be sent for. The examples quoted in illustration 

 of general principles are naturally mostly taken from' 

 the British Isles, but there are many of great interest 

 from other parts of the world, particularly from the 

 United States and the British Dominions beyond the 

 Seas. 



After an introductory chapter and some general 

 remarks on rainfall and atmospheric impurities, the 

 author states some general geological considerations, 

 and proceeds to describe the modes of dispersal of 

 rain on the surface and underground, special refer- 

 ence being made to rivers and underground channels, 

 swallow holes, pipes, bournes, dumb-wells, and 

 springs. Then follows a chapter on surface sources 

 of supply, which include storage of rain-water, sup- 

 plies from springs, streams, and rivers, ponds,' dew- 

 ponds, and lakes and reservoirs. The geological in- 

 terest increases in the next chapter, on underground 

 sources of water supply— wells of all kinds— and then 

 follow three chapters on the water-bearing strata of 

 England, working backwards through the geological 

 record. The succeeding chapter, on prospecting for 

 water, applies the information already provided to the 

 selection of sites for wells and borings, having regard 

 to the quantity and quality of water required, the 

 geological uncertainties underground, and, incident- 

 ally, to the belief that trustworthy aid can be obtained 

 from various methods of water divining. This is, 

 in our opinion, the most valuable chapter in the 

 book; the hints as to the examination of particular 

 districts and the diagrams illustrating local peculiari- 

 ties which may be met with are extremely clear, and 

 will form a useful warning to the non-expert of the 

 danger of trusting too much to apparent simplicity 

 of structure. 



The next section of the book concerns itself with 

 the water supply in polar, arid, and other regions, 

 and in islands, where special conditions arise ; a non- 

 geological chapter refers shortly to the quality of 

 water and the examination thereof by chemical and 

 bacteriological analysis ; and, lastly, we have a chapter 

 of great interest on mineral waters, i.e. waters which 

 contain in solution more than the 60 or 70 grains 

 per gallon which marks the "potable" limit. 



A final chapter adds to the growing body of evidence 

 NO. 2l8l, VOL. 8/] 



which may one day be deemed sufficient to justify the 

 constitution of a National Water Board, which would 

 enable " (he various independent authorities dealing 

 with the conservancy of rivers, with canals, drainage, 

 sanitary matters, and water supply," to act to some 

 extent in concert. 



A useful glossary and bibliography and a satisfac- 

 tory index are appended. 



In reviewing a suggestive book of this kind it 

 would, of course, be easy to embark upon a discus- 

 sion of many things which, as the author is always 

 careful to point out when he comes to them, are still 

 largely matters of opinion, but space forbids more 

 than the mere laying of emphasis upon one or two 

 points. We note the need for further investigation of 

 the conditions of percolation, and the solvent action of 

 water in a permeable formation such as limestone. 

 Where the limestone formation is exposed it would 

 seem that, the solvent power of the percolating water 

 being quickly lost, solution takes place chiefly along 

 cracks or joints, which are opened out into fissures, 

 caves or underground channels being formed where 

 the rock material is strong, and subsidence occurring 

 where it is weak; but where the permeable formation 

 is overlain by an impermeable, it appears that perco- 

 lation takes place with great slowness, and water 

 obtained by boring through the upper strata is not 

 quickly replaced from a distance. The analytical 

 work of Mr. W. W. Fisher and Dr. J. C. Thresh 

 in the oolites in Oxfordshire and the chalk under 

 London is extremely significant; it suggests impor- 

 tant conclusions in connection with, e.g. the lowering 

 of the water-table under London, the outflow of water 

 from the chalk in Kent and Hertfordshire and in 

 other parts of England where similar structures occur. 

 With regard to maps showing underground con- 

 lours, we agree that contours delineating the upper 

 surface of covered water-bearing formations are valu- 

 able, and that an extension of work similar to that 

 of Mr. W. H. Dalton is desirable. But we think 

 that Mr. Woodward underestimates the usefulness of 

 maps representing underground water-contours, which 

 give much information as to the direction of flow of 

 underground water and its variations from time to 

 time under varying rainfall and pumping. 



We note few slips, but it may be worth pointing 

 out that the New River derives much of its supply 

 from an intake from the Lea, and the Glencorse reser- 

 voirs largely supplement the Crawley springs in con- 

 tributing water from the Pentland Hills and 

 Edinburgh. h. N. D. 



PARASITISM. 



Survival and Reproduction : a new Biological Outlook. 



By H. Keinheimer. Pp. x + 410. (London : J. M. 



Watkins, 1910.) Price 7s. 6d. net. 

 ' I 'HE plentifully quoted pages from the writings of 

 -»- Darwin, Kropotkin, and others contained within 

 the structure of this book form far more than its 

 skeleton. Their presence justifies the statement that 

 the work contains many luminous passages and much 

 translucent information. 



That part of the work which spatially connects the 



