Tom Swift and His Great Oil Gusher by Victor Appleton

AT FIRST the well went down rapidly. The earth was soft and sandy near the surface, and with even an ordinary drilling outfit progress would have been fairly rapid. But Tom's newly perfected drill fairly ate its way through the soil, "like a gimlet going through a nice soft piece of cheese," as Ned expressed it. They were all delighted with the performance of the new invention, and promised themselves an early and successful strike.

But this rapid progress did not keep up long. After the first hundred feet or so, the ground became harder, and they often encountered rocks that slowed up even Tom's marvelous drill. It kept hammering away, though, and gradually thrust through obstacles that would have splintered and shattered any ordinary well-boring outfit.