| http://www.w3.org/ns/prov#value | - casing for drilling and collapsible to a diameter less than that vof said casing for withdrawal through the latter, means for locking said casing to said drill stem for rotation thereby, said locking means including shoes carried by said drill stem and operable to engage said casing, actuating means for causing locking engagement of said shoes with said casing, said actuating means comprising com
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