VOL. LXXIV.] PHILOSOPHICAL TRANSACTIONS. 463 



soft quality, and on being drawn, has a degree of warmth unusual in common 

 well water. It remains yet to be determined whence that warmth proceeds ; but 

 as it proved wholesome, the circumstance is fortunate for the soldiers of the 

 garrison, as they will not be liable to complaints that are so frequent among 

 troops (as often happens at Dover Castle) from imprudence in drinking great 

 quantities of very cold well water. 



The King's Wells at Landguard-Fort were begun and finished in the year 

 1/82. The peculiar situation of this fort made it very unlikely that springs of 

 fresh water could ever be found, there being great reason to think, that the 

 out-fall of the Ipswich and Manningtree rivers, which unite before they reach 

 the sea, was formerly on the Suffolk side of the fort, but is now on the Essex 

 side ; and as the garrison in ancient writings, is described to have been built on 

 the Andrew's Sand, there appeared little probability of any filtration of water 

 through it, except that of the sea. It however seemed proper to try the possi- 

 bility of sinking through it, to endeavour to find a hard bottom, similar to that 

 discovered at Sheerness, fresh water being of great consequence to the defence 

 of the place. The work was accordingly begun ; but about the same time, in 

 making the excavation of a ditch for one of the batteries, at a very few feet from 

 the upper surface of the sand, a small quantity of fresh water was perceived ; 

 and it was chance that led to a discovery of its freshness, from one of the 

 labourers happening to taste it. On examining further, it was found that the 

 quantity of water on sinking was considerable, and that it appeared perfectly 

 fresh. The well-sinkers were then ordered to proceed to this depth at another 

 place, where they found a like appearance of good water ; and the quantity was 

 so great, as to render it very difficult to keep the bottom of the well, at 12 feet 

 deep, dry enough to sink farther. Every exertion however was used, and with 

 great labour a well was sunk to the depth of low water mark at spring tides, 

 about 18 feet from the upper surface of the sand ; when, to the surprize of every 

 person, the water that rose from the bottom became, on a sudden, entirely salt. 

 This put an end to the work for a time, as it seemed impossible to penetrate 

 deeper. It was now directed that sand should be thrown into the well, to bring 

 it a little above what had been the lowest fresh water line (12 feet from the upper 

 surface) and then the water was drawn out which had mixed. After this, the 

 filtration into the well became again perfectly fresh, and in equal quantity to the 

 first appearance. This was therefore fixed as the greatest depth (12 feet); and 

 another well was sunk at 40 feet distance, with a horizontal brick drain, having 

 holes left in the sides for filtration, to collect the water, and the bottoms of both 

 wells were secured with hard materials ; that the whole supply of water might 

 be reduced to the drain, which is constructed to prevent as much as possible the 

 mixture of sand with the water, and is found to answer the desired end. This 



