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accidents of water breaking in, or the roof falling. There is 
no bad gas to cause explosions. It is not accidents of this 
kind that are referred to in speaking of land subsidence in 
the salt districts. The whole of the manufactured salt is 
literally mined by water. A constant stream of water 
running over the rock salt to the pumping stations becomes 
saturated with the salt that it takes up on its way. Being 
pumped up, the salt is gained by the method of evaporation 
before described. It is evident that in gaining the salt in 
this manner, by water, no provision can be made for the 
support of the roof of overlying earths, as is done by pillars 
in the ordinary mine. The brine streams, or brine ‘ runs ’ 
as they are called, resemble brooks and rivulets into which 
the waters run from all sides and drain the surface. The 
course of these underground streams is marked by a corre- 
sponding depression on the surface of the ground. The land 
sinks more rapidly directly over the brine runs than else- 
where, though there is a gradual lowering of the surface of 
the rock salt generally, even out of the line of the runs— 
exactly as there is a gradual lowering of the surface of the 
land by the solid earths and sands carried away by the 
water draining off it. The salt, however, being so much 
more soluble than earths, the process is much more rapid. 
In some cases the overlying earths follow the gradually wast- 
ing rock salt continuously, and the subsidence on the surface 
is regular and continuous; in other cases where there happens 
to be a tenacious “ flag” or other stiff and solid earths, the 
superincumbent mass remains suspended over the brine run 
for a long time. As soon, however, as the weight of the sus- 
pended mass overcomes the tenacity of the marl or flag, a 
sudden sinking of the whole overlying earths takes place, 
and a large hole reaching up to the surface is formed, which 
in time becomes filled with water. 
In recent years a number of these holes have been formed 
in the neighbourhood of Winsford and North wich. In the 
neighbourhood of North wich they have been formed chiefly 
over old mines. Instead of the hollow being made naturally, 
as near Winsford, by the ordinary brine run, it has been made 
artificially by the miner. In both cases, however, the sudden 
