11 



one part there is a bed of marl wliich remains as a pro- 

 tuberance all around the shaft. Above and below — but 

 especially below — the salt is much eaten away. The water 

 is now prevented from running down, consequently the 

 dissolving action is suspended and the shaft remains to 

 show the cause of the destruction of so many other shafts.* 

 Another shaft (Piatt's Hill) recently collapsed. Just prior 

 to falling in, it was inspected and the rock salt was found 

 to be eaten away to a distance of from 30 to 40 feet from 

 the centre of the shaft, and a huge cavern or cavity, many 

 feet high, was left. This soon collapsed, and now, although 

 men were employed for several months filling in earth to 

 keep the hole choked and to prevent it drawing in a 

 neighbouring tramway, it still keeps sinking, showing that 

 solution by water is yet going on. About 200 yards from 

 Piatt's Hill — in a district called Dunkirk — another shaft 

 collapsed nearly two years ago. This was a brine shaft. 

 The fresh water found access to the rock salt and dissolved 

 it, leaving a huge cavity. The shaft sank suddenly, taking 

 in the surface and burying the pump trees, &c. I have just 

 finished lining with bricks, set in cement, a portion of a 

 shaft in which fresh water had commenced to attack the 

 rock salt. Here the shaft being new and the water small in 

 quantity, the damage has been but slight. So needful is it 

 to prevent the water running over the rock salt and causing 

 serious damage, that owners of salt mines which have not 

 been worked for more than 20 years are yet obliged to pump 

 up weekly, or at longer intervals, the water caught in 

 reservoirs placed in the shaft for this purpose. The old 

 mines being abandoned and the shafts timbered across and 

 filled in, were in process of time forgotten. Solution by 

 water, however, has been going on and the rock salt has 



* The marl mixed with the rock salt fell to the bottom of the shaft where 

 it forms a large heap, whilst the partly saturated water formed pools on the 

 floor of the mine in which beautiful salt crystals are now forming. 



