An assembly comprising: a structural member having a longitudinal axis and configured to conduct a pressurized fluid in an operational state; and an apparatus comprising a housing member including a first end, a second end, and at least one protective enclosure configured to accommodate at least one device, the housing member being configured to move on the structural member parallel to the longitudinal axis in the operational state with a substantially frictionless reciprocating motion, the housing member being rotationally registered to the structural member , a first pneumatic isolator (12-5) formed at the first end, and a second pneumatic isolator (12-5) formed at the second end, characterized in that the apparatus is adapted to apply a first pressurized fluid portion of the pressurized fluid to the first pneumatic isolator (12-5) in the operational state to drive the housing member toward a second direction of the reciprocating motion, the apparatus is adapted to apply a second pressurized fluid portion of the pressurized fluid to the second pneumatic isolator (12-5) in the operational state to drive the housing member toward a first direction of the reciprocating motion opposite the second direction, and the substantially frictionless reciprocating motion is a function of external stimuli, the first pressurized fluid portion and the second pressurized fluid portion, wherein the housing member is substantially isolated from the external stimuli. a structural member having a longitudinal axis and configured to conduct a pressurized fluid in an operational state; and an apparatus comprising a housing member including a first end, a second end, and at least one protective enclosure configured to accommodate at least one device, the housing member being configured to move on the structural member parallel to the longitudinal axis in the operational state with a substantially frictionless reciprocating motion, the housing member being rotationally registered to the structural member , a first pneumatic isolator (12-5) formed at the first end, and a second pneumatic isolator (12-5) formed at the second end, a housing member including a first end, a second end, and at least one protective enclosure configured to accommodate at least one device, the housing member being configured to move on the structural member parallel to the longitudinal axis in the operational state with a substantially frictionless reciprocating motion, the housing member being rotationally registered to the structural member , a first pneumatic isolator (12-5) formed at the first end, and a second pneumatic isolator (12-5) formed at the second end, characterized in that the apparatus is adapted to apply a first pressurized fluid portion of the pressurized fluid to the first pneumatic isolator (12-5) in the operational state to drive the housing member toward a second direction of the reciprocating motion, the apparatus is adapted to apply a second pressurized fluid portion of the pressurized fluid to the second pneumatic isolator (12-5) in the operational state to drive the housing member toward a first direction of the reciprocating motion opposite the second direction, and the substantially frictionless reciprocating motion is a function of external stimuli, the first pressurized fluid portion and the second pressurized fluid portion, wherein the housing member is substantially isolated from the external stimuli. <EOS>