| 摘要 |
A sub for connection into a drill string which has a cable extending along the outside of the string to the location of the sub and then extending downwardly within the string beyond the sub. The sub includes two members which are connectable to upper and lower portions of the drill string and are detachably connectable to one another, preferably by a surrounding threaded sleeve, with the cable extending between the two members in sealed relation from the exterior of the first member to the interior of the second.
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