Abstract
This paper discusses the effects of radial conduction on thermal diffusivity measurements obtained by the pulse method. The solution to the mathematical problem of transient two‐dimensional conduction which follows an instantaneous disk source of energy at one surface of an infinite slab is used to determine the half‐time as a function of boundary heat losses. This value is then compared with the half‐time obtained when radial conduction is neglected. The magnitudes of the effects for various ratios of pulse radius to slab thickness are tabulated.