Question

In early eighteenth-century Britain, the extraction of tin and copper from deep subterranean mines in Cornwall was severely hampered by persistent water inundation. To mitigate this flooding, mine operators increasingly turned to Thomas Newcomen’s atmospheric steam engine, first introduced in 1712. Although Newcomen engines were thermodynamically inefficient—consuming immense quantities of coal because the main cylinder had to be alternately heated and cooled during every stroke—Cornish mine owners found their deployment economically viable due to specific local operational adjustments.

Unlike coal-rich regions such as Newcastle where fuel costs were negligible, Cornwall possessed no native coal deposits, making fuel transportation via sea extraordinarily expensive. To offset these exorbitant fuel expenditures, Cornish mining consortia introduced an integrated water-recirculation system. Under this arrangement, the engine’s primary pump lifted mine water into elevated surface reservoirs; this stored water was subsequently released to drive overshot waterwheels that powered auxiliary ore-crushing machinery. Furthermore, rather than running the engines continuously, Cornish engineers calibrated the pumping frequency strictly to coincide with local tidal influx cycles in drainage adits. This scheduled operation enabled the engines to run intermittently at maximum mechanical load, avoiding the severe efficiency losses associated with continuous low-load idling. Consequently, these tailored infrastructural practices sustained the commercial viability of Cornish mineral extraction for several decades preceding James Watt’s patenting of the separate condenser in 1769.

According to the passage, Cornish mine operators offset the high cost of transporting fuel to their mines by doing which of the following?