I WAS glad to see Vin Malone’s letter about the burnt material on walls from early steelmaking.
The material is known as crozzle and the kilns were called cementation furnaces. There were once over 200 of them in Sheffield steelworks. The furnace in Doncaster Street is the city’s only complete survivor.
The furnaces at Bower Spring are a Scheduled Ancient Monument, owned and preserved by the South Yorkshire Industrial History Society.
About £35,000 has been spent on repairing them, with funding from English Heritage, the Town Trustees and the Graves Trust. We hope for more funds but so far we have been disappointed.
Derek Bayliss, Hon. planning and development officer, South Yorkshire Industrial History Society