"Equations for the heat-transfer coefficient existing at the interface of two metals in contact are discussed. The results of applying the equations (with a graphical determination of the geometric parameters) to an iron--aluminum contact are presented. A method is given for performing the graphical analysis by means of a general purpose analog computer. Data are included that were obtained by applying this method to Blanchard ground stainless steel surfaces in contact. Statistical analysis was applied to surfaces to determine the geometric properties of the contact as a function of root-mean-square roughness and method of surface preparation."