1 



464 PHILOSOPHICAL TRANSACTIONS. ' [aNNO lOjS, 



The depth of the springs is various ; some rise on the top of the ground 

 which are not so salt as others : those that are in the pits we make use of, are 

 various also. The great pit, which is called Upwich Pit, is 30 feet deep, in which 

 are 3 distinct springs rising in the bottom. The pit is about 10 feet square; the 

 sides are made with square elms, jointed in at the full length, which I suppose 

 is occasioned by the saltness of the ground, which appears to me to have been 

 a bog, the surface of it is made of ashes. That it was originally a bog I am in- 

 duced to believe ; for, not many years since digging to try the foundation of a 

 seal, for so we call the houses we make salt in, I thrust a long staff over head. 



There are no hot springs near us : and the brine is generally colder than 

 other water ; yet it never freezes, but the rain water that lies on the brine in 

 extreme hard frosts will freeze, though not much. 



I never observed nor heard of any shells in the earth. For the nature of the 

 soil about the town on the lower side, it is a black rich earth, under which 2 or 

 3 feet is a stiff gravelly clay ; then marl. Those that make wells for fresh 

 water, if they find springs in the marl, they are generally fresh; but if they 

 sink through the marl, they come to a whitish clay mixed with gravel, in 

 which the springs are more or less brackish. 



In the great pit at Upwich, we have at once 3 sorts of brine, which we call 

 by the names of first-man, middle-man, and last-man, these sorts being of differ- 

 ent strengths. The brine is drawn by a pump; that which is in the bottom is 

 first pumped out, which is that we call first-man, &c. A quart measure of this 

 brine weighs 29 ounces troy, but of distilled water only 24 ounces. This brine 

 yields above a fourth part salt; so that 4 tuns of brine make above 1 tun of salt. 

 The two other sorts less, or 28 ounces. And the pit yields 450 bushels of salt 

 per day. In the best pit at Netherwich a quart of brine weighs 28 ounces and 

 a half; this pit is 18 feet deep, and 4 feet broad, and yields as much brine 

 every 24 hours, as makes about 40 bushels of salt. The worst pit at Nether- 

 wich is of the same breadth and depth as the former; a quart of brine out of 

 which weighs 27 ounces, and yields as much brine daily as makes about 30 

 bushels of salt. 



The fuel which was heretofore used was all wood ; which, since the iron works, 

 is destroyed, that all the wood at any reasonable distance will not supply the 

 works one quarter of the year; so that now we use almost all pit-coal, which is 

 brought to us by land, from 13 or 14 miles distance. 



The vats we boil the brine in are made of lead, cast into a flat plate, 5 feet 

 and a half long, and 3 feet over; then the sides and ends beaten up, and a little 

 raised in the middle, which are set upon brick-work, called ovens, in which is a 

 grate to make the fire on, and an ash-hole which we call a trunk. In some seals 



