Preliminary piezoresistance and piezo-Hall-effect measurements have been made on three relatively pure samples of n-type silicon over the temperature range 77-300Â°K to strains ∼1/2%. The room-temperature value of the ratio of the saturation resistivity at large stress to the resistivity at zero stress confirms Long's estimate of the relative strength of the "across the zone face" umklapp scattering in intravalley acoustic phonon scattering, rather than a value an order of magnitude larger estimated by Dumke. Additionally, from the dependence of resistivity upon stress at 77Â°K, the value 8.3±0.3 eV is found for the shear deformation potential tensor component Ξu. The dependence of both resistivity and Hall coefficient on stress at 77Â°K can be fitted quite well by theoretical expressions, deduced under certain reasonable simplifying assumptions, over the entire range of stress. © 1963 The American Physical Society.