elliptical approximationa described in 1f (3) (b) below, however, its use was extremely linited due to tho great uncertainty as to its applications for high yield ovmts. 2 the operaticn progresa.d, 1t becams apparcnt that a more meticulous mothod wie needsi to clecriy define ‘he fa}j-cut from the high yields, The elliptical appreccimaticn set-od and 4a linear extension of the surface R/DEX were woth limited by che fact that they are built upon the ground cere winds. «. new and dynamic method was needed to take into account the changes in the wind systcus as particles drifted farther and farther from ground tero. ..t the request of the task force Radsafe oftieer, Dr, Geelen Pelt of LiSL and 1 7.1, working directly with Major 0. W. Stopinski, Meteoralogis* from the Task Force Weather Central, undertook the development of such « method. The ext resalt (static end dynamie plots) 19 indicated in Inclosure 2 of Teb D as used on the last three shots of the C.STLE series, It should be noted that all mothods except the dynamic plot (Inclosure 2, Tab D), were used on the last Ave shots, ent all methods on the last three shots. This ws dome to evaluate each method in ite relation to others and because no single method waevuffietentiy tried and proved to the complete satisfaction of all. Tn thie respect the Radseafe portion of the Camand Bricfings became somevhah ecuplisated, although viewed in retrospect, it sppears thata better appreciation of all the factors involved in the fall-cut aechenion arose from this examination of the various different® spproechos to the problem. For exemple, the limitations of same methods were highlighted by others, and the presentation of old techniques similtenecusly with the new, served to exphasise the need for better answere and the