When James Henderson presented his paper ‘On the Methods Generally Adopted in Cornwall in Dressing Tin and Copper Ores‘ in 1858, it was to update the classic 1826 paper ‘On the manipulation to Which the Ores of Tin and Copper are Subjected in the Central District of Cornwall‘ by W.J. Henwood. Henderson not only described new processes and methods in great detail, but included carefully executed drawings of the equipment used, and of their operators. Transcribed here, his paper gives a rare insight into the operations at surface of the tin, copper, and lead mines of the mid 19th century. For the mining historian or engineer there is much to glean from the text and illustrations. We are also reminded of the importance of the role and skill of the ore dressers; usually women and children, and miners who were no longer fit to work underground.