What lies beneath the ground? Our poor eyesight cannot penetrate even an inch into the soil, so for centuries, fortune-seekers have tried every way imaginable to see below the surface. Whether searching for mineral veins, groundwater, or buried treasure, people have looked for ways to avoid the plodding and backbreaking process of digging. They have followed dreams, seers, dowsing rods, and advice from the spirit world. When petroleum became an item of commerce, oil-hunters took to all the...