15 
salt manufacture, and during the 17th century references 
are frequent, especially in the Philosophical Transactions of 
the Royal Society. Rock salt was discovered in 1670, and 
in 1721 the river Weaver was made navigable from Frods- 
ham through Northwich to Winsford. After this period 
the manufacture steadily but not rapidly increased until 
1825, when the duty was taken off salt. Immediately a 
great advance was made which continued till 1844, when 
the East Indian market was opened to English salt and the 
manufacture grew still more rapidly. The alkali trade 
caused another rapid advance so that at the present time the 
quantity manufactured is fully ten times as large as at the 
commencement of the present century. 
The districts of Cheshire in which salt is made are in the 
valleys of the Weaver, Dane, and Wheelock, and this has 
always been the case, for with the exception of a small 
manufacture of salt at Droitwich for a limited time, none has 
ever been made except in close proximity to these streams. 
The Weaver valley is the most important, and at Winning- 
ton, Anderton, Marston, Wincham, Northwich, Leftwich, 
Winsford, and Nantwich salt is now being made, or has been 
made in times past. Since 1847 Nantwich has ceased to 
manufacture salt. 
Middlewich is at the junction of the Croco with the Dane, 
which latter stream is a tributary of the Weaver. In the 
neighbourhood of Sandbach, at Wheelock, Lawton and the 
surrounding district, salt is made. These places lie in the 
Wheelock valley, a tributary of the Dane. 
The Cheshire salt beds lie in the Keuper marls, though 
they are not co-extensive with these marls. The red or 
triassic marls of Cheshire lie in a kind of basin compared 
to an elongated saucer with its longest axis lying in a nearly 
north and south direction. The best known and most im- 
portant beds of rock salt are about the centre of this basin 
in the neighbourhoods of Northwich and Winsford. At 
