(Vertical Pattern) or Barton’s App. The Torsion Apparatus (Searle's or Barton's) features a sturdy steel frame on a cast iron base with leveling screws. It includes a 900mm long, 5mm diameter test rod secured by a 3-jaw chuck at the top and a torsional drum at the bottom, which can be rotated using scale pans and frictionless pulleys. Three graduated circular scales with clamps and three pointers are provided for precise measurements.