Moreover, the localisation of various departments of the trade within Lancashire is still more remarkable. Not only have the old mills in which spinning and weaving were carried on together given way before division of labour, but the two processes are mostly conducted in different districts, the former in the towns immediately around Manchester, the latter in the more distant northern circuit. Nor is the specialisation confined to this. Spinning is again divided according to the coarser and finer qualities of yarn. The Oldham district, with Ashton, Middleton, and other towns south of Manchester are chiefly confined to the medium numbers. Bolton, Chorley, Preston, and other northern towns undertake the finer numbers. In weaving there is even more intricate division of labour, each town or district specialising upon some particular line of goods.[120] Moreover, it must be borne in mind that the substitution of the factory for the domestic system and the continual enlargement of the average factory indicates an important progressive concentration. So the cotton industry does not in fact cover nearly so large a local area as when it was one-hundredth the size. The same is true of the other chief branches of the textile and metal industries. Nor is it only in the manufactures that towns and districts are closely specialised. The enormous increase of commerce due to machinery of manufacture and of transport requires the specialisation of certain towns for purely commercial purposes. London, Liverpool, Glasgow, and Hull are more and more devoted to the functions of storage and conveyance. Manchester itself is rapidly losing its manufacturing character and devoting itself almost exclusively to import and export trade. The railway service has made for itself large towns, such as Crewe, Derby, Normanton, and Swindon. Cardiff is a portentous example of a new mining centre created when the machine development of England was already ripe.