Making a total of 853,750 cubic yds. This represents 176·5 acres of 1 yd. thick.
This is entirely independent of the rock-salt, which, at a low estimate, equals 120,000 tons per annum, or, say, 75,000 cubic yds., or 15·5 acres of 1 yd. thick.
In these calculations no allowance has been made for wastage, and this is very large. During the year every pan requires picking from six to twelve times, the stoved oftener than the common. This necessitates the pan being swept out and an enormous quantity of brine wasted. Besides this, the pan scale contains a large percentage of salt. Again, in drawing the salt out of the pans a large quantity of brine is wasted. Add to this also the leakage in pipes, overflow of cisterns, leakage through defective pans, etc., and the total of wastage will be very large. It is scarcely possible to estimate this, but if we calculate 10 per cent. we shall be under the mark. Thus, for waste, we may set down 136,600 tons. This would represent 85,075 cubic yds., or 17·65 acres 1 yd. thick.
We thus see that 209·65 acres of rock-salt 1 yd. thick is every year consumed in the Cheshire salt district.
CHAPTER VI
THE CHESHIRE SUBSIDENCES
The salt industry of Cheshire may be divided into three periods, viz.: the natural brine period, the rock-salt period, and the prepared brine period. From Saxon times up to the last quarter of the seventeenth century the manufacture of white salt from brine had been continued without interruption, but the output had never been large. In 1675 the production of the three “Wiches” was returned at 20,000 tons, and all the evidence shows that the total annual make had never exceeded 30,000 tons. In 1670, rock-salt was discovered in the county, and for the next hundred years, although brine continued to be worked, rock-salt mining was the chief producing industry. With the collapse of the mines, the salt proprietors turned once more to the brine supply, upon which Cheshire has since risen to its present commercial eminence as one of the great salt-making centres of the world.
In 1670, a rock of natural salt was discovered on the Marbury Estate, about one mile north of Northwich, by one John Jackson, of Halton, who was engaged at the time in “searching for coals on behalf of the Lord of the Soil (or Manor, I should say), William Marbury, of Marbury, Esquire.” The event was communicated to the Royal Society by Mr. Adam Martindale in a letter dated 12th December, 1670. He added that the liquid issuing from the rock was “a vigorous sharp brine beyond any of the springs made use of in our salt works,” and, being asked by the Royal Society to visit the place and send a further report, he subsequently wrote: “The rock of salt, by the relation of the workmen, is between 33 and 34 yards distant from the surface of the earth, about 30 whereof are already digged and they hope to be at the Flagg which covers the salt rock about three weeks hence.... That piece of natural salt which the instrument brought up (divers saw it, a pure ore) was as hard as alum and as pure.”
The records of the rock-salt mining period are singularly incomplete, inexact, and disappointing. It is not known for certain which was the first mine sunk after the discovery of the salt-bed in 1670. It may have been the one which is described as “very near to a small brook which drains Marbury Mere and joins the Witton Brook, near the Buttevant Bridge on the Marbury Estate.” Or it may have been another early mine which was situated “close to a small runnel or gutter which runs into this small brook near the Dairy House Farm but passes across the land of Mr. Lyons and over the old Marston mine.” If the curious inquirer is not yet satisfied with these conjectures, he is further informed that there is yet another subsidence of an old mine, “close to the Forge Lane or road leading to Budworth across the Fields, where the road branches off at the cottages and salt-works of Mr. Lyons’ property ... and this mine is probably the earliest sunk.”
But if little is known about the beginning of the salt-mining industry in Cheshire, there is not much more to be learnt about its development and ultimate decay. To-day, only the Adelaide Marston Mine at Northwich is working, and of the nineteen mines that were open in Cheshire in 1881, only nine were at work, while from an undated plan and key showing the rock-salt mines in the Northwich district, which was probably published a few years earlier, we learn that of the fifty rock-salt mines that had been abandoned, twelve had been sunk to the bottom bed and the rest had been worked as top-bed mines.
