[19] See 'Journal of Royal Agricultural Society,' vol. xii. p. 595. CHAPTER XII. Production of a knife--Manufacture of iron--Raising coal--The hot-blast--Iron bridges--Rolling bar-iron--Making steel--Sheffield manufactures--Mining in Great Britain--Numbers engaged in mines and metal manufactures. We have been speaking somewhat fully of agricultural instruments and agricultural labour, because they are at the root of all other profitable industry. Bread and beef make the bone and sinew of the workman. Ploughs and harrows and drills and thrashing-machines are combinations of wood and iron. Rude nations have wooden ploughs. Unless the English labourer made a plough out of two pieces of stick, and carried it upon his shoulder to the field, as the toil-worn and poor people of India do, he must have some iron about it. He cannot get iron without machinery. He cannot get even his knife, his tool of all-work, without machinery. From the first step to the last in the production of a knife, machinery and scientific appliances have done the chief work. People that have no science and no machinery sharpen a stone, or bit of shell or bone, and cut or saw with it in the best way they can; and after they have become very clever, they fasten it to a wooden handle with a cord of bark. An Englishman examines two or three dozens of knives, selects which he thinks the best, and pays a shilling for it, the seller thanking him for his custom. The man who has nothing but the bone or the shell would gladly toil a month for that which does not cost an English labourer half a day's wages. And how does the Englishman obtain his knife upon such easy terms? From the very same cause that he obtains all his other accommodations cheaper, in comparison with the ordinary wages of labour, than the inhabitant of most other countries--that is, from the operations of science, either in the making of the thing itself, or in procuring that without which it could not be made. We must always remember that, if we could not get the materials without scientific application, it would be impossible for us to get what is made of those materials--even if we had the power of fashioning those materials by the rudest labour. Keeping this in mind, let us see how a knife could be obtained by a man who had nothing to depend upon but his hands. Ready-made, without the labour of some other man, a knife does not exist; but the iron, of which the knife is made, is to be had. Very little iron has ever been found in a native state, or fit for the blacksmith. The little that has been found in that state has been found only very lately; and if human art had not been able to procure any in addition to that, gold would have been cheap as compared with iron.