 Some mouldstones have additional smaller hollows on their surface; these are traditionally assumed to be for assaying purposes, but some authors have suggested that they may have been for making small ingots for selling illicitly to avoid tin coinage, the tax on white, or refined tin.The only properly documented find of a tin ingot from Dartmoor has a diagonal hole through it which matches the supposed practice of placing a stick in the mould when pouring in the molten tin.The stick would burn away leaving the hole which would be used to lever out the solid ingot from the mould and would later be useful to tie up the ingots for carriage.