3. _The Nature of the Commodity._--When all modes of conveyance were slow the degree of specialisation depended largely upon the keeping quality of the goods. From this point of view hardware and textiles are obviously more amenable to local specialisation than the more perishable forms of food. Where conveyance is difficult and expensive a commodity bulky for its value is less suitable for local specialisation in production than one containing a high value in small weight and bulk. So cloth is more suitable for trade than corn;[34] and coal, save where navigation is possible, could not be profitably taken any distance.[35] The common commodities consumed, as food, fuel, and shelter, were thus excluded from any considerable amount of specialisation in their production. § 8. Turning from consideration of the attributes of goods and of the means of transport which served to limit the character of internal trade and determine the size of the market, let us now regard the structure of the market, the central object in the mechanism of internal commerce. The market, not the industry, is the true term which expresses the group of organically related businesses. How far did England present a national market? How far was the typical market a district or purely local one? The one great national market town was London. It alone may be said to have drawn supplies from the whole of England, and there alone was it possible to purchase at any season of the year every kind of produce, agricultural or manufactured, made anywhere in England or imported from abroad. This flow to and from the great centre of population was incessant, and extended to the furthermost parts of the land. Other large towns, such as Bristol, Leeds, Norwich, maintained close and constant relations with the neighbouring counties, but exchanged their produce for the most part only indirectly with that of more distant parts of the country. The improving communication of the eighteenth century enabled the clothiers and other leading manufacturers to distribute more of their wares even in the remotest parts of the country, but the value paid for their wares reached the vendors by slow and indirect channels of trade, passing for the most part through the metropolis. But while London was the one constant national market-place, national trade was largely assisted by fairs held for several weeks each year at Stourbridge, Winchester, and other convenient centres. At the most important of these the large merchants and manufacturers met their customers, and business was transacted between distant parts of the country, including all kinds of wares, English and foreign. Thus we had one constant and two or three intermittent avenues of free national trade. The great bulk of markets, however, were confined within far smaller areas.