By the mid-eighteenth century, Shadwell Spa was established, producing sulphurous waters, in Sun Tavern fields. As well as being used for medicinal purposes, salts were extracted from the waters and used by local calicoprinters to fix their dyes. By the mid-eighteenth century, many houses in Shadwell had been rebuilt. "Seamen, watermen and lightermen, coalheavers and shopkeepers, and ropemakers, coopers, carpenters and smiths, lived in small lathe and plaster or weatherboard houses, two storeys and a garret high, with one room on each floor"; the average rent was £2-7. In 1768, London coal workers who were protesting for higher wages began shooting at the landlord of the Roundabout Tavern in Shadwell; as a result, seven of them were hanged in the Sun Tavern fields. Their execution was witnessed by around 50,000 spectators, the largest crowd at a hanging since the hanging of Laurence Shirley, 4th Earl Ferrers in 1760. in 1794, many houses on the Ratcliffe Highway were destroyed by a fire which "consumed more houses than any one conflagration has done since the Great Fire of London", and also destroyed many boats, and around £40,000 of sugar.