18 Rev. A. Irving— Water Supply from the Bagahot Beds, etc. 



A. good instance of the purity of water drawn from the Upper 

 Sands is found in the well at Finchampstead Rectory. This well 

 is about 50 feet deep, and the geological structure of the district 

 shows that the well reaches the water-bearing level of the passage- 

 beds between the Middle and Upper Bagshot strata, the water being 

 held up by the clayey strata which occupy a high horizon in the 

 Middle Bagshot Series.^ The water from the well is so pure and 

 soft that J can only compare it with water drawn from the crystalline 

 rocks of the Alps above the glaciers. It has only mere traces of 

 mineral matter ; it does not become turbid by exposure to the air ; 

 and it does not take up iron in solution from pipes or boilers con- 

 structed of that metal, and precipitate it afterwards as peroxide, on 

 exposure to the air, as the water from the strata lower down does. 

 This of course we ascribe at once to the absence of vegetable-matter 

 in solution in the water. But now comes an interesting distinction 

 which must be drawn. Though the generalization referred to above 

 has had its truth amply confirmed by later facts, the converse of the 

 proposition is onl3'^ true within certain limits ; that is to say, we 

 have no right to assume that all the water drawn from the Upper 

 Bagshot Sands is pure and wholesome. Experience shows us that 

 many wells, which penetrate into the Upper Sands only, yield water 

 loaded with vegetable-matter in solution. An example of this is 

 found at ray own house. The water is drawn here from a well 

 17 feet in depth, and I have made quite sure, from the levels of 

 tlie country as laid down by the Military Ordnance Survej'^, as well 

 as from actual excavations, that the well does not penetrate any but 

 the Upper Sands, which theoretically, and so far as the evidence 

 given in my former paper seemed to carry us, ought to yield good 

 water. Yet after the well had been disused for a time, the water 

 was putrid, and could only be characterized by its smell and other 

 properties as ' bog- water.' A little reflection soon showed that this 

 was due to the shallowness of the well combined with the close 

 proximity of a portion of the ancient forest-lands of this region ; so 

 that within a few yards of the well on two sides there remained a 

 dense coating of peaty matter covering the surface of the ground, 

 clothed with a dense growth of heather, moss, and lichen. By 

 clearing a portion of the ground, and by opening the well per- 

 manently to the air, the water has been so far improved as to have lost 

 its offensive smell and taste. It still, however, is so much charged 

 with vegetable-matter in solution, as shown both by chemical tests, 

 and by the amount of iron which it takes up (especially when heavy 

 rains follow a period of drought) from the kitchen-boiler, as to be 

 objectionable for dietetic purposes. Facing the difficulty, I have 

 discovered a process (the details of which ai'e known at present only 

 to myself and the Patent Office) whereby the water can be made 

 as clear, pui'e, and palatable as water drawn from the crystalline 

 rocks ; the water from my well being (after treatment) as good in 

 every way as that from the deeper well at Finchampstead Eectory 



^ See communication by the author to the Geologists' Association, " On the 

 Bagshot Strata of the London Basin," Five. Geol. Assoc, vol. viii. No. 3. 



