 He described prospecting for ore veins and surveying in detail, as well as washing the ores to collect the heavier valuable minerals, such as gold and tin.The work shows water mills used in mining, such as the machine for lifting men and material into and out of a mine shaft.Water mills found application especially in crushing ores to release the fine particles of gold and other heavy minerals, as well as working giant bellows to force air into the confined spaces of underground workings.