English: The Compressor House at South Wheal Francis Inside this building is the concrete framework which cradled long departed engines. The compressor provided compressed air to drive rock drills in the mine. In earlier mining operations drilling rock was a slow process driven only by a miner hammering on a metal bar. The invention of the compressed air rock drill hugely increased productivity in the mines but the original drills proved deadly to miners from lung disease caused by the rock dust put into the air by the drills. Later drills pushed water down to the drill head to damp down the dust.