cable-tool drilling

a drilling method in which the hole is drilled by dropping a sharply pointed bit on bottom. The bit is attached to a cable, and the cable is repeatedly dropped as the hole is drilled.

cable-tool drilling

(from the article `petroleum production`) Early oil wells were drilled with impact-type tools in a method called cable-tool drilling. A weighted, chisel-shaped bit was suspended from a cable ...
Found on http://www.britannica.com/eb/a-z/c/2
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