Two different materials M₁, M₂ of equal dimensions (length L and uniform cross-sectional area A ) having thermal conductivities k₁ and k₂ respectively are connected together through a bolt M₃ . The bolt (length =2 L , area =A / n ) is of another material with thermal conductivity k₃ such that n 1 . The left sides of the material M₁ and M₃ are kept at the temperature T₁ whereas the right sides of the material M₂ and M