80 ME. W. E. BALDWIN-WISEMAN ON [Feb. 1907, 



6. The Influence of Peessebe and Poeosity on the Motion of 

 Seb-Sebface Watee. By William Ralph Baldwin- Wiseman, 

 M.Sc, ABSocM.Inst.CE., F.G.S. (Bead June 27th, 1906.) 



[Plate V— Map.] 



Contexts. 



Page 



I. Historical Introduction 80 



II. Experimental Data on Porosity and the Flow of 



Interstitial Water 81 



III. Experimental Data on Variation of Pressure in 



the Interstices of a Bock 94 



IV. Field-Observations 97 



V. Bibliography 103 



I. HlSTOEICAL INTBODECTION. 



Since the early part of the last century the question of the behaviour 

 of underground water has received the attention of numerous 

 investigators, whose labours have resulted in the compilation of 

 a most voluminous and scattered bibliography, comprising records 

 of field-observations, experimental data, and mathematical deduc- 

 tions, many of which are difficult of access. I have therefore, 

 although deeply conscious of the omission of the names of many 

 worthy investigators, endeavoured to summarize briefly the more 

 important investigations on this subject, with the view rather of 

 outlining the work, than of giving a full record of workers. 



In 1837, Robert Stephenson (l) 1 first noted the formation of a 

 cone of depletion in the water-logged sands of the Inferior Oolite, 

 during the progress of the construction of the Kilsby Tunnel on the 

 London & North- Western Railway ; and in a later report to the 

 London & Westminster Water Company, he remarked upon the high 

 absorptivity of the Chalk and the intermittent nature of its surface- 

 streams. 



The first systematic well-measurements were made by Bland (2) 

 in 1831, along two parallel lines from Sittingbourne to Maidstone ; 

 and ten years later Clutterbuck prepared a somewhat similar section 

 on a line from Dunstable to Watford. 



In 1851 Ansted (3) experimentally determined the rate of 

 percolation of water through Chalk, under comparatively-low 

 pressures ; and seventeen years later, in 1868, Isaac Roberts (4) 

 published a few figures showing the effect of pressure on the rate 

 of flow of water through the Red Sandstone of the Liverpool district. 



In 1856 Darcy (5) stated that the rate of percolation of water 

 through sand varied directly as the pressure, or head, on the water, 

 but inversely as the thickness of the bed traversed. Hagen (6) 

 questioned the first part of this proposition, while agreeing as to 



1 Numerals in parentheses after authors' names, throughout this paper, refer 

 to the Bibliography, § V, p. 103. 





