210 A Sketch of the Natural History of 



being in the focus to which the other radiates, il must fa* 

 cilitate the escape of caloric from the other, by quickly ab- 

 sorbing all that is sent to it bv radiation from tiiat oiher 

 body. In the common experiment the thermometer is the 

 radiating body, and the ice the absorbent. A. T. 



XXX. A Sketch of the Natural History of the Cheshire 

 Rock- Salt District. By Henrv Holland, Es(^. Ho- 

 norary Member of the Geological Society*. 



J. HE vast beds of fossil or rock-salt, which are found in 

 different parts of the county of Chester, form undoubtedly 

 the most important and peculiar feature in the mineraloav 

 of this district. In offering to the notice of the Geological 

 Society some remarks upon these mines, it may be proper 

 to premise, that in a Survey of Cheshire, which I had the 

 honour of drawing up for the Board of Agriculture, I en- 

 tered at considerable length upon the subject of their na- 

 tural history, and upon the manufacture of white salt from 

 the brine springs to which they give rise. It will be my 

 present object to consider more especially the mineralogical 

 situation and characters of the Cheshire rock-salt ; and 

 though the repetition of some statements must necessarily 

 occur ; this, in the case of a work only partially known, 

 can, I conceive, be attended with little disadvantage. 



Character of the Country surrounding the Salt Mines. 



In speaking of the general situation of the Cheshire salt 

 mines, it will be proper to state some facts with respect to 

 the nature of the surrounding country, that their mineralo- 

 gical relations may more clearly be understood, and an op- 

 portunity given to speculate upon the probable origin of 

 these important strata. The southern parts of Lancashire, 

 the northern extremity of Shropshire, and the whole of the 

 intervening county of Cheshire, form in conjunction one 

 vast tract of plain country, interrupted by few elevations, 

 and these inconsiderable in size and extent. The area of 

 this plain may be regarded as extending nearly fifty mile* 

 from north to south, and as having an average breadth of 

 twenty-five or thirty miles. Its eastern boundary, as more 

 immediately regards the county of Chester, is a high range 

 of sandstone hills, stretching from north to south along 

 the borders of Derbyshire and Staffordshire ; connected oa 



• From the Transactions of the Geological Society, vol. i. 



the 



