For a long column of fireclay brick, 6m×6m on a side and steady-state conditiou. four main surfaces are maintained at 300K, and two corner sufacces are adiabatic. For Δx=Δy=2m and the thermal conductivitry of brick is 1.0 W/m K, working out the following problems. [1] Using the enagy balance method to derive the node equations. [2] Presenting the Gauss-Seidel iterative procedure for the above equation set. [3] Expessiug the heat flow rate from all surfaces with the column height,L.