Searle’s Torsion Apparatus (Horizontal Pattern) is used to determine the modulus of rigidity (shear modulus) of a wire. The apparatus consists of a horizontal metallic rod or shaft suspended by a thin wire fixed at one end. The other end is attached to a circular scale and vernier to measure angular displacement. Weights or a twisting couple can be applied to produce torsional oscillations. By measuring the period of oscillation and knowing the system's dimensions and mass, the modulus of rigidity of the wire material can be calculated. It is commonly used in physics labs for studying torsional behavior.