MANUFACTURE OF SALT IN CHESHIRE. 13 



No water is ever found on this salt; the "rock head/ 

 as it is called, is perfectly dry. 



It is almost impossible to say what the area of these 

 beds of rock salt is. Judging, however, by the subsidence 

 of the land, and taking into consideration the furthest 

 points at which salt has been proved by shafts, I have 

 come to the conclusion that the Northwich beds occupy 

 at least three square miles, and contain in the aggregate 

 about 900,000,000 tons — the upper bed 380,000,000, the 

 lower 520,000,000. The Winsford district is more diffi- 

 cult to determine ; but, being again guided by the distinct 

 subsidences of the land, there cannot be less than six miles 

 of salt beds, containing at least 1,900,000,000 tons of salt. 

 It is quite impossible to estimate the quantities of rock 

 salt in the Nantwich, Middlewich, and Lawton districts, 

 as there are no mines, and only in Lawton has the salt 

 rock been bored through. There are several other districts 

 where salt must exist, as is shown by the subsiding of 

 the land. The figures givea, which are the merest ap- 

 proximations, show that practically the salt beds are in- 

 exhaustible. 



The first, or top-rock salt, was discovered in 1670 ; and 

 very shortly after this mines were worked, but not to any 

 large extent. It was not until 1 7 2 1, when the river Weaver 

 was made navigable, that the rock salt could be largely 

 utilized. In the year 1732 there were sent down the Weaver 

 9322 tons of rock salt. The quantity shipped down the 

 river increased year by year until in 1778 it reached 54,000 

 tons. In 1 78 1 the bottom or lower rock salt was discovered ; 

 and all new mines were sunk to it, the quality being better. 

 After the commencement of the present century the top 

 mines ceased to be worked; and now only one is known to 

 exist. Nearly the whole of these top mines were destroyed 

 by the breaking-in of water or brine at the shafts. One 



