wash-drill

from The Century Dictionary.

• noun A boring-apparatus for sand or loose earth in which a jet of water under high velocity is forced through a tube and issuing at the open lower end in the soil washes the latter from the path of the tube as it is pressed forward by its own weight or by a mechanical pressure. The water escapes around the outside of the tube and carries the loosened material to the surface with it. Also called a water-jet and similar to the latter when used in hydraulic mining.