Abstract: A stethoscope chestpiece has a body member, a tubular shaft, and an indexing detent. The body has a plurality of microphones each of which has a opening at its apex and a central recess. The tubular shaft is rotably secured within the central recess and has an opening in its wall that aligns selectively with one of the openings from the microphones. The sound conveying detent is mounted transversely within the shaft and aligned with the opening in the shaft wall. The indexing detent has a hollow cylindrical element and spring. The hollow cylindrical element has an open bottom and a seat end having an opening. The seat end is beveled and extends beyond the opening in the shaft wall to engage the body. When the seat end is aligned with a selected one of the openings from the microphones it seats to hold the opening from the microphone in alignment with the opening in the seat end to create a sound passageway into the tubular shaft.

Abstract: A single use thermal switch having a tubular casing within which a mechanical isolation cage is axially movable. The cage is normally urged by a helical compression spring against a fusible pellet which melts at a temperature at which it is desired to disconnect the electrical circuit. An electrically conductive contact member extending transversely through the isolation cage is normally urged by a helical compression spring toward one end of the cage and against the end of one electrical lead that is coaxial with the casing. The contact member is foldable along a line across its center. The force of the contact member pressed against the end of the lead urges the contact member to fold to cause the ends thereof to be forced against the inside wall of the casing to establish electrical connection between the casing and the lead through the contact member.

Abstract: A switch device utilizing independently acting biasing members to position a conductor to close a circuit between a pair of leads and maintain such closed circuit until a switch activating member such as a meltable pellet reaches a circuit opening state whereupon further independent biasing action causes the conductor member to assume a circuit open position.