Reviews — Records of London Wells. 175 



a special inquiry, not only into the causes of the depletion, but also 

 of the unequal distribution of water in the Chalk of the London 

 district, has become urgent ; and the various matters are now 

 discussed in a philosophic spirit by Mr. Barrow in part i, the 

 inti'oduction to this memoir. 



The volume is divided into three parts, and we may conveniently 

 commence by a brief description of the contents of parts ii and iii, 

 which constitute the bulk of the memoir. Part ii (pp. 34-90) is 

 a Catalogue of Published London Wells, the object being to record 

 their precise sites, and to give details of supply and other information 

 that in many instances had not previously been published. The actual 

 records of the strata are not repeated, but some additional particulars 

 relating to them are here and there inserted. The 6 in. London 

 County map of the Ordnance Survey in the first place has been 

 utilized to record the positions of the wells. Each sheet of the map 

 has been divided in 2 in. squares with letters and numbers, and 

 these sheets are deposited in the Geological Survey Office for public 

 reference. By a series of abbreviations the data relating to each well 

 are concisely noted in the memoir. They indicate where the record 

 was published, the site of the well as marked on the 6 in. sheet, 

 the elevation of the ground, the depth of well (shaft) and boring, 

 diameter of bore, position of Chalk surface above or below Ordnance 

 Datum, water-level, and yield of water in gallons per hour. 



Part iii is a descriptive account (rather than list) of wells, mostly 

 new, but a few previously published. Of most interest geologically 

 are the records of the deep borings at Beckton Gasworks, East Ham ; 

 Chiswick ; Southall ; and Willesden (two): All of these five borings 

 after penetrating the Gault entered rocks in all probability of 

 Devonian or Old Red Sandstone age, at depths respectively of 975, 

 1,1201-, 1,135, 1,098, and 1,153 feet from the surface. At Southall 

 the strata contained fish-remains of Old Red Sandstone age. Saline 

 waters were encountered in these old rocks at East Ham and at 

 Willesden (Stonebridge Park). A brief account of the Palaeozoic 

 floor is given in the Introduction (part i). Among the records of the 

 wells and borings no mention is made of Blackheath Beds, but they 

 may be represented in the strata passed through at East Greenwich 

 Portland Cement Works and at Shirley (pp. 113 and 203). 



Part i (pp. 1-33), the readable portion of the memoir, is an essay 

 mainly on the water-bearing capacity of the Chalk in different parts 

 of the London District ; and Mr. Barrow takes the opportunity of 

 describing the methods of constructing the old and new wells and 

 the headings in the Chalk. He points out how the water in the 

 lower sandy portion of the Woolwich and Reading Beds, as well as 

 that in the Thanet Sands (where present), may be directly connected 

 with that in the Chalk. He discusses the character of the water 

 obtained directly from the Thanet Sands at considerable depths, 

 a matter dealt with by Mr. Whitaker in his Geology of London^ 1889 

 (vol. i, p. 513), and more recently by Dr. J. C. Thresh, whose views 

 Avere adversely ci'iticised in The Surveyor for July 26, 1912. There 

 is no doubt that the Thanet Sand water is mainly derived from that 

 which enters the Chalk outcrop, and that it has undergone chemical 



