The increase of vegetable and animal produce, though great, seems small when compared with the increase of our mineral wealth. In 1685 the tin of Cornwall, which had, more than two thousand years before, attracted the Tyrian sails beyond the pillars of Hercules, was still one of the most valuable subterranean productions of the island. The quantity annually extracted from the earth was found to be, some years later, sixteen hundred tons, probably about a third of what it now is. [71] But the veins of copper which lie in the same region were, in the time of Charles the Second, altogether neglected, nor did any landowner take them into the account in estimating the value of his property. Cornwall and Wales at present yield annually near fifteen thousand tons of copper, worth near a million and a half sterling; that is to say, worth about twice as much as the annual produce of all English mines of all descriptions in the seventeenth century. [72] The first bed of rock salt had been discovered in Cheshire not long after the Restoration, but does not appear to have been worked till much later. The salt which was obtained by a rude process from brine pits was held in no high estimation. The pans in which the manufacture was carried on exhaled a sulphurous stench; and, when the evaporation was complete, the substance which was left was scarcely fit to be used with food. Physicians attributed the scorbutic and pulmonary complaints which were common among the English to this unwholesome condiment. It was therefore seldom used by the upper and middle classes; and there was a regular and considerable importation from France. At present our springs and mines not only supply our own immense demand, but send annually more than seven hundred millions of pounds of excellent salt to foreign countries. [73] Far more important has been the improvement of our iron works. Such works had long existed in our island, but had not prospered, and had been regarded with no favourable eye by the government and by the public. It was not then the practice to employ coal for smelting the ore; and the rapid consumption of wood excited the alarm of politicians. As early as the reign of Elizabeth, there had been loud complaints that whole forests were cut down for the purpose of feeding the furnaces; and the Parliament had interfered to prohibit the manufacturers from burning timber. The manufacture consequently languished. At the close of the reign of Charles the Second, great part of the iron which was used in this country was imported from abroad; and the whole quantity cast here annually seems not to have exceeded ten thousand tons. At present the trade is thought to be in a depressed state if less than a million of tons are produced in a year. [74]