HOW TIN WAS EXTRACTED
later. When sufficient had been collected, long troughs were sunk in the "calm," or native clay, and these were filled with charcoal; then the tin ore was laid on this charcoal, and either more of this latter was heaped above, or else peat was piled
up, with layers of ore. Finally the whole was kindled. No bellows were used, but a draught through the channel kept the whole glowing, and the metal ran through the fire into the bottom of the hollow, or ran out at the end, as this rude furnace was constructed on an incline.