Heat And Thermodynamics

Rate of flow of heat through a cylindrical rod is $\mathrm{H}_1$. The temperature of the ends of the rod are ' $\mathrm{T}_1$ ' and ' $\mathrm{T}_2$ '. If all the dimensions of the rod become double and the temperature difference remains the same, the rate of flow of heat becomes ' $\mathrm{H}_2$ '. Then $\mathrm{H}_2=$