§ 13. The specialisation of certain districts within the town, though far less rigid than in the mediæval town, is very noticeable in the larger centres of industry. Natural causes often determine this division of localities, as in the case of the riverside industries, brick-making and market-gardening in the outer suburbs. Round the central station in every large town, for convenience of work and life, settle a number of industries related to the carrying trade. Every trade, market, or exchange is a centre of attraction. So the broking, banking, and the general financing businesses are grouped closely round the Royal Exchange. Mark Lane and Mincing Lane are centres of the corn and tea trades. In all town industries not directly engaged in retail distribution there are certain obvious economies and conveniences in this gregariousness. Agents, travellers, collectors, and others who have relations of sale or purchase with a number of businesses in a trade find a number of disadvantages in dealing with a firm locally detached from the main body, so that when a district is once recognised as a trade centre, it becomes increasingly important to each new competitor to settle there. The larger the city the stronger this force of trade centralisation. Hence in London, untrammelled by guild or city regulations, we find a strong localisation of most wholesale and some retail businesses. In retail trade, however, the economic gain is less universal. Since retail commodities are chiefly for use in the home, and homes are widely distributed, the convenience of being near one's customers and away from trade competitors is often a predominating motive. Shops which sell bread, meat, fish, fruit, groceries, articles which are bought frequently and mostly in small quantities, shops selling cheaper articles of ordinary consumption, such as tobacco, millinery, stationery, and generally shops selling articles for domestic use, the purchase of which falls to women, are widely dispersed. On the other hand, where the articles are of a rarer and more expensive order, when it is likely that the purchaser will seek to compare price and character of wares, and will presumably be willing to make a special journey for the purpose, the centralising tendency prevails in retail trade. So we find the vendors of carriages, pianos, bicycles, the heavier articles of furniture, jewellery, second-hand books, furs, and the more expensive tailors and milliners clustering together in a special street or neighbourhood.