A reprint of the privately-produced 1936 edition (with additional material) describing the early cave diving exploration of Wookey Hole Caves by Graham Balcombe, Penelope Powell and others using "hard hat" pump-fed diving equipment.
A reprint of the privately-produced 1936 edition (with additional material) describing the early cave diving exploration of Wookey Hole Caves by Graham Balcombe, Penelope Powell and others using "hard hat" pump-fed diving equipment.