Swansea is a town of very considerable importance.  It has a large foreign and home trade, and contains a number of furnaces for the smelting of copper, the ore being imported from Cornwall and Devonshire, and even from Australia and other foreign places.  Five or six thousand ships visit it every year.  Several canals and railways connect it with other parts of the country.  It is not surprising that the wreck chart should show a number of black dots off its harbour.