xx. WATER SUPPLY. 501 



of lime gathered by the rain in its percolation through the cal- 

 careous gravel and its slow current on the subjacent clay. But 

 it was not otherwise contaminated. On the contrary, at present, 

 wells in Oxford, not a few, are justly to be objected to as injured 

 by soakage of filthy solutions and mixtures from sources at the 

 surface too near the wells. Such solutions may be expected to pass 

 in the porous gravel even to considerable distances, and to exhibit 

 themselves in the wells, and give proof of their existence, not only 

 by reaction on chemical tests, but by injurious effects on the whole 

 process of digestion. 



On this account the ancient method of supply to some of the 

 colleges from the Hinksey springs was to be commended, though 

 the water was hard, that is to say, charged with carbonate of lime. 

 The modern method of supply from the Railway Lake, which is 

 filled by nature after filtration through the gravel in the bed of the 

 valley, is still better; but it is to be regretted that houses and 

 offensive drains have been permitted to usurp a place too near the 

 source which ought to be above all suspicion. 



Want of water is not seldom experienced in some parts of the 

 country round Oxford in particular seasons. This happens not 

 uncommonly on the line of the Forest marble clays, where shallow 

 wells are feebly supplied from the thin clay-bedded stones, and 

 in the broader tracts of Oxford and Kimmeridge clays, which, if 

 not covered by gravel, have no permanent natural springs. The 

 usual remedy, ' to sink deeper/ is not always successful in the first 

 case, because the great oolite below allows water to pass away freely 

 by particular channels to certain favoured localities probably at 

 some distance ; and in the other case, either no water is met with, 

 or it is scanty and of bad quality through admixture with sulphates 

 of lime and iron, and perhaps magnesia. If, in this difficulty, the 

 sinking be continued till the clay, however thick, be penetrated, 

 and the subjacent oolite be reached, it is very probable that a 

 moderate supply will be found, and that the water will rise in 

 the well, and fill it as a convenient reservoir, or even overflow with 

 some force. Thus an 'Artesian' well may sometimes be had; but 

 no one should undertake the trial without good advice, of a practical 

 geologist acquainted with the district d . 



d The Kev. J. C. Clutterbuck, M. A., of Long Wittenham, possesses thorough 

 knowledge on questions of this kind. 



