Byram (1959) makes a third reduction for radiation. There are two arguments for not making this latter reduction: (1) there is no sound basis available for estimating radiant heat as a proportion of the total energy output of individual fires of different intensities,and (2) radiation is not really a loss, but contributes greatly to fire behavior (Van Wagner 1972b, 1973). This reduction is suggested if some special purpose requires an estimate of only convective heat output (Van Wagner 1972 b).