He replied, “all bodies exposed in a clear night must undoubtedly radiate as much of their heat during a storm as in the most perfect calm; but, whenever radiation is going on, the air is more or less warmed by it; and consequently wind, which is only air in motion, serves to bring a continual stream of its warm particles into contact with those bodies. This restores almost as much heat as they had lost, and prevents the deposition of dew; for, you know, dew is nothing but the moisture of the atmosphere condensed by meeting with colder substances; and, therefore, whatever tends to equalize the temperature of the air, and of those substances, must obstruct the formation of dew.”
We breakfasted at Kidderminster, and saw every part of the carpet manufactory; but the chief interest of the day has been a magnificent inclined plane on the Shropshire canal, which my uncle was so good as to go out of the direct road to shew us. It is a slope of 350 yards in length, with a fall of 70 yards, connecting the canal on the high ground with the canal on the lower level; and the boats, being placed in a kind of cradle upon wheels, are allowed to roll gently down the inclined plane, or are drawn up by the power of a small steam engine. By this contrivance three great savings are effected, he said. First, the prodigious expense of building twenty-one locks, which would be required for that height; secondly, the time occupied in passing through all those locks; and, thirdly, the quantity of water which is wasted every time a lock is opened, and which, in some parts of the country, it is very difficult to replace in a dry summer.
Wood Lodge.
16th.—So far our journey has been most agreeable in every way. My uncle and aunt not only stop wherever there is any thing to see, but they tell me what to observe, because they know that, through ignorance, I might overlook the things which deserve the most attention. Only think, mamma, of their having actually come into Cheshire, in order to shew me a salt-mine. My uncle promised it many months ago, and he never forgets a promise to any of us, even about a trifle. Some old friends of theirs, Mr. and Mrs. L., live at this pretty place, where we arrived yesterday evening. We were received with warm affection; and I was considered as one of my aunt’s children, and treated with equal kindness.
As soon as an early breakfast was over, we all drove or rode to Northwich, about five miles from this; and between the fineness of the day, the good nature of both new and old friends, and the complete novelty of going down into a mine, it has been a delightful expedition indeed. By the way, I must tell you, that there was some little hesitation about the ladies going down: there are few mines, my uncle says, that would be very suitable to such visits; but when it can be effected with propriety, he approves of their learning the realities of life. We are such imaginative beings, he says, that truth is necessary to steady our minds.
By my uncle’s directions, I put on an old dress of one of the miner’s wives, over my own, to prevent it from being soiled by the iron chain and the bucket in which we were let down. By the time I was near the bottom, I began to hear the confused sound of the people below, and to see the indistinct flickering of candles; and on looking up, the day light admitted from above by the opening through which we had descended looked smaller than the moon. The walls, and pillars left occasionally to support the roof of the mine, quite disappointed my imagination; for they are of a dirty brown colour, instead of the brilliant white I had expected. In a few places, indeed, they sparkled a little in the gleams of the candles which we carried.
After walking about in various directions, and feeling as if in the crypt of some large church, we came to where the men were working. They were just going to light the train to blast off a rock of salt; and I assure you it was very near the place where we stood; but we were secured behind a projecting point. The roof, there, was not above twenty feet high, and the sound was very grand, continuing to reverberate at intervals for a minute and a half.
The salt lies in strata, from between which water is always trickling; and the white salt used for eating is made from this water, which is pumped up above ground, either by steam or horse power. It is then put into what are called preparing pans, where it is brought to the degree of heat requisite for separating the earthy impurities. These subside to the bottom, and leave the brine clear, and ready to be afterwards evaporated in the salting pans, which are shallow, and I am sure twenty or thirty feet long.
Some years ago the excise duty was twenty-five times the actual value of the salt; but that is now taken off, and therefore great additional quantities are raised for agricultural or other purposes. I hope this will benefit the workmen, who seem to be very poor, for their cottages are very wretched; each of them, however, is surrounded by a nice little garden; and my aunt made me observe, that the thrift, or sea-pink, flourishes there, as well as where it grows naturally in the salt atmosphere near the seashore.
I can write no more now. We continue here to-morrow, I believe; and the next day we shall go on to Llangollen.