W. H. HucUeston — Recent Wells in Dorset. 249 



This is, of course, only a very generalised section, but the chief 

 point to note is that in the Wimborne Waterworks the boring was 

 carried down only 40 feet into the Chalk. 



"We now come to the consideration of the Bournemouth Waterworks, 

 by far the most important work of the kind hitherto attempted in 

 Dorset. In this case the vertical section shows 96 ft. 9 in. of superficial 

 and Tertiary beds down to the Chalk — an amount of Tertiaries slightly 

 in excess of the adjacent boring. It must not be forgotten that although 

 these are called the " Bournemouth " Waterworks, the water is derived 

 from the Dorset Chalk, and subsequently conveyed into the adjoining 

 county. 



The following is the vertical section : — 



Superficial Beds... 

 Lower Tertiaries 



Soft Chalk (Upper Heading) 



Hard Chalk 



Band of flint 



Chalk to bottom of well (LoAver Heading) 



Trial boring in Chalk ... 



Thus the "Bournemouth" Well is 210 feet, whilst the Wimborne 

 Well is 130 feet deep. 



Some of the particulars of the "Bournemouth" Waterworks may 

 be gathered from a study of Fig. 5.^ A 21 inch trial borehole was 

 commenced in 1894 and finished in 1895; boring was continued to 

 a depth of 223 feet, and it was noticed that the greatest increase in the 

 yield of water took place shortly before arriving at that depth, the 

 Chalk removed appearing to be much softer. The well was started in 

 1896, and in February, 1899, on its attaining a depth of 210 feet, 

 a 6 inch trial boring was sunk to a further depth of 45 feet, i.e. to 

 255 feet from the surface. The Chalk, however, was found to be 

 very compact at this depth, and, as there was no sign of more water 

 at the lower level, the sinking of the well was stopped at 210 feet 

 from the surface and the bottom concreted. The bottom of the well, 

 therefore, is about 145 feet below O.D. 



The horizontal section also serves to show the character of the 

 Headings. The Lower Heading was first commenced in 1899 at 

 a depth of 195 feet from the surface, and excavated on opposite sides 

 of the main shaft. In the course of a few months a total length of 

 about 800 feet was attained, and the flow of water was considered 

 equal to about Ij million gallons per day. In July, 1899, fresh 

 Headings (the Upper Heading) were started at a level of 155 feet 

 from the surface in softer Chalk, much fissured ; the result by 

 November was a flow of water somewhat exceeding 1^ million gallons 

 per day. At present I have no precise information as to the level 

 produced by natural hydrostatic pressure in the well, but the pumping 

 arrangements are so complete that this level is soon lowered, not only 



1 The horizontal section of the Bournemouth Waterworks at S\^imborne is 

 reproduced, by the kind permission of the Editor of Water and of Mr. Cripps, the 

 engineer of the works. (See paper by Mr. Cripps in Water, September, 1906.) 



