Abstract: A well logging instrument includes a body member supporting one or more arm members which may be biased outwardly against the sidewalls of the borehole. The arm members may be held in a closed position, adjacent the body member, during entry into a borehole by a heat sensitive retaining member. As the instrument is exposed to borehole temperature the heat sensitive retaining member will within a preselected temperature range release the arm member allowing the arm members to expand outwardly from the body member into contact with the sides of the borehole.

Abstract: Apparatus is provided for collecting a plurality of samples of fluids in earth formations traversed by a well bore. The sampling apparatus includes an elongated body member adapted to carry a telescopically extensible and retractible fluid admitting probe which is selectively placed in sealing engagement with potentially producible earth formations. The fluid admitting probe has a central passage in fluid communication with a first fluid sample chamber and a plurality of outer passages which are selectively communicated with formation fluid sample storage chambers within the body member.