282 FOSSIL FOOD 



pure and crystalliiio rock-sjilt. The absftnce of fossils shows 

 that animals must have had as bad a time of it there as in 

 the Dead Sea of our modern Palestine. The Droitwich 

 brine-pits have been known for many centuries, since they 

 were worked (and taxed) even before the Norman Conquest, 

 as were many ether similar wells elsewhere. But the 

 actual mining of rock-salt as such in England dates back 

 only as far as the reign of King Charles II. of blessed 

 memory, or more definitely to the very year in which the 

 • Pilgrim's Progress ' was conceived and written by John 

 Bunyan. During that particular summer, an enterprising 

 person at Nantwich had sunk a shaft for coal, which he 

 failed to find ; but on his way down he came unexpectedly 

 across the bed of rock-salt, then for the first time discovered 

 as a native mineral. Since that fortunate accident the beds 

 have been so energetically worked and the springs so 

 energetically pumped that some of the towns built on top 

 of them have got undermined, and now threaten from year 

 to year, in the most literal sense, to cave in. In fact, one 

 or two subsidences of considerable extent have already taken 

 place, due in part no doubt to the dissolving action of rain 

 water, but in part also to the mode of working. The mines 

 are approached by a shaft ; and, when you get down to the 

 level of the old sea bottom, you find yourself in a sort of 

 artificial gallery, whose roof, with all the world on top of 

 it, is supported every here and there by massive pillars 

 about fifteen feet thick. Considering that the salt lies 

 often a hundred and fifty yards deep, and that these pillars 

 have to bear the weight of all that depth of solid rock, it 

 is not surprising that subsidences should sometimes occur 

 in abandoned shafts, where the water is allowed to collect, 

 and slowly dissolve away the supporting columns. 



Salt is a necessary article of food for animals, but in a 

 far less degree than is commonly supposed. Each of us 



