Reviews — C. E. Be Ranee's Water Supply. 87 



special works by Prof. Prestwicli, Prof. Ansted, Mr. Lucas, Mr, S. 

 Hughes, and other private authors, having more or less reference to 

 Avater supply. 



Many valuable reports were obtained by the Congress on National 

 Water Supply convened by the Council of the Society of Arts in 

 1878-79. See Journ. Soc. of Arts, 1879. To this Congress Mr. De 

 Eance was a contributor, and the papers then read, and another 

 " On the Secondary Rocks of England as a source of Water Supply " 

 (Manch. Geol. Soc, March, 1878), combindti with the "Lectures on 

 Water Supply" to the Wigan Mining School in 1876, form the 

 basis of the present work. The object being to show not only the 

 character and quantity of the water supplied to every town in Eng- 

 land and Wales, but to afford data for estimating the volume of 

 water available and the quantity required for consumption (accord- 

 ing to the population census of 1881) in the different groups of river- 

 basins, by carefully describing the area of the principal geological 

 formations, and the amount of rainfall in each basin. 



The first chapter treats of rainfall and its percolation. As all 

 fresh-water is derived either from rain or snow, the distribution of 

 the rainfall (less the loss by evaporation and absorption by plants 

 and animals), and its subsequent accumulation either in lakes, rivers, 

 or in underground circulation, are the available sources of supply. 



Mr. De Ranee states — " According to Mr. Symons' map, the rain- 

 fall of England exceeds 25 inches per annum throughout the entire 

 area lying west of a line ranging from Shields to Reading, whilst 

 west of a line trending from Shields to Start Point, the rainfall 

 around the Lower Palaeozoic rocks forming the elevated tracts of the 

 English Lake District, of Wales, and of Dartmoor, amounts to more 

 than 75 inches per annum. With so large an area, receiving so 

 abundant a rainfall, the existing absence of an efficient water-supply, 

 not only for our larger cities, but for our rural population, becomes 

 a matter of surprise, and an inquiry into the causes, a subject of 

 considerable importance " (p. 1). 



The Hyetographical map indicates the annual amount of rainfall 

 arranged under six divisions, varying from 23 to 90 inches. 



After speaking of the disadvantage of large artificial reservoirs 

 from their sometimes covering extensive areas of good meadow 

 ground, in comparison to natural lakes as reservoirs, the author says. 

 "The great value and agricultural character of the land consisting of 

 the Newer Palasozoic, Secondary and Tertiary rocks, make an inquiry 

 into the amount of water they are capable of yielding when 

 penetrated by deep wells, which do not necessitate large expanses 

 of reservoir space, a matter of considerable interest. Classified ac- 

 cording to their water-yielding characters, they may be described as 

 impermeable, pervious, and suprapervious, the latter consisting of 

 impermeable strata resting on a pervious rock" (p. 5). 



The Hydro-geological map (p. 30) shows the areas occupied by 

 these rocks, to which is added a " partially porous " division. 



The storage capacity of rocks is also considered, and a table (p. 19) 

 shows the varying quantity of water held in the pores of various 

 rocks, per cubic foot. 



