23 



the last ten years ; and in the Dunkirk district of North- 

 wich, the scene of the great subsidence of 1880, when the 

 water not only found its way into the old Dunkirk mines, 

 but broke into the salt mine called Piatt's Hill (which was 

 being worked) by a weak place in the dividing wall of salt, 

 and flooded the mine, over fifteen acres in extent, causing 

 enormous destruction on the surface in the immediate 

 neighbourhood. The ground is still rapidly sinking in both 

 these districts, and the area of the lakes is increasing daily. 

 If there are any buildings on the sinking ground they soon 

 present fissures and cracks, and literally fall to pieces. The 

 amount of property destroyed in this way is enormous. It 

 would make my paper far too long to point out all the 

 ruin and destniction caused in the salt districts by the 

 solution of the salt and its pumping up in the form of brine 

 for its manufacture into white salt. 



In Germany, when the brine is not strong enough, i.e. not 

 fully saturated, boreholes are put down to the salt, by 

 which means the brine becomes of full strength. As most 

 of the German salt works are on a very small scale com- 

 pared with those in England, and scattered over an enor- 

 mous area, instead of being concentrated in one or two spots, 

 as in Cheshire, the results of brine pumping have not shown 

 themselves on a very extensive scale. In Cheshire salt had 

 been made for ages before any visible subsidences occurred ; 

 but when about 1780 the manufacture increased, then visible 

 subsidence manifested itself, and in direct proportion as the 

 manufacture has increased so has the sinking, till now it 

 extends over an area of several square miles. 



V. — Water conveyed artificially to deep scdt beds and then 

 pumped up again. . 



Of late years, owing to beds of salt being discovered 



