First, it may be employed in raising, manufacturing, or purchasing goods, and selling them again with a profit. The capital employed in this manner yields no revenue or profit to its employer, while it either remains in his possession, or continues in the same shape. The goods of the merchant yield him no revenue or profit till he sells them for money, and the money yields him as little till it is again exchanged for goods. His capital is continually going from him in one shape, and returning to him in another; and it is only by means of such circulation, or successive changes, that it can yield him any profit. Such capitals, therefore, may very properly be called circulating capitals. Secondly, it may be employed in the improvement of land, in the purchase of useful machines and instruments of trade, or in such like things as yield a revenue or profit without changing masters, or circulating any further. Such capitals, therefore, may very properly be called fixed capitals. Different occupations require very different proportions between the fixed and circulating capitals employed in them. The capital of a merchant, for example, is altogether a circulating capital. He has occasion for no machines or instruments of trade, unless his shop or warehouse be considered as such. Some part of the capital of every master artificer or manufacturer must be fixed in the instruments of his trade. This part, however, is very small in some, and very great in others, A master tailor requires no other instruments of trade but a parcel of needles. Those of the master shoemaker are a little, though but a very little, more expensive. Those of the weaver rise a good deal above those of the shoemaker. The far greater part of the capital of all such master artificers, however, is circulated either in the wages of their workmen, or in the price of their materials, and repaid, with a profit, by the price of the work. In other works a much greater fixed capital is required. In a great iron-work, for example, the furnace for melting the ore, the forge, the slit-mill, are instruments of trade which cannot be erected without a very great expense. In coal works, and mines of every kind, the machinery necessary, both for drawing out the water, and for other purposes, is frequently still more expensive.