The object of this investigation will be to obtain curves which will permit easy calculation of the heat transfer through insulation uniformly applied to cylindrical enclosures with flat ends. The curves are to cove the usual range of ratios of cylinder diameter to length and of insulation thickness to cylinder diameter. It is to be assumed that the insulation is homogeneous, that the inside and outside surfaces of the insulation are isothermal, and that the thermal conductivity is constant. The investigation will be confined to a calculated solution for the steady state. Since no calculus solution has been found for this case, the relaxation method will be employed. / M.S.