this can be dane by summation of hodosraph winds if these are more readily accessible, Likewise, tho distances fram the altitude points on the hodegrapa to points of fall-out interest con bo quickly measured with the ruler, giving the values of r. Knowing $ end r, ome can easily camute paondq. With the aid of a family of curves of ae ams oa (rp)? (ece Piz. 1) for several values of p, one ean rapidly interpolate the values that mst be added up at any lcoection, The expomential factor drops off very rapidly with q, and after wriing out 4 few cases, one can tell, fram en inspection of the hodograph-cmeatcll plot, some of the altitude peints that can ba neslected in the eanputaticn. 6. Pig. 2 and Toblo 1 illustrates the application of the mathod to observed at shot time, E NECT.2 shot, using the marked 10, The points on Piz, 2 2, xX, are the 10,000 ft, 20,066 t%, o- @ altitude points on o the hodozragh for particles fallin; 50,000 ft per hour. «4. particle starting, for example, at 30,000 ft above ground sero, and falling undor the influence of winds tut not diffusion, would land at the point marked 90. The value of S$, the horiaontal distence travelled, is estimated by summing the distance between the suceessive pcints from ground sero to point 30. In caloulating q in Table 1, some values are omitted as beycnd the ranze of Piz. 1. More values are dropped, as too small to bother with, in entering the quantities ay (a5. the are the surface et ts“ff i +fua oncentrations that would be produced if the initial central concantraticns C,) were all unity. When the method was tried cut on Y.NKES, it was found i ei eewas was & teasthan eSer lees than that o o in 2, not by a presomt time the oly explanation that can be ie the hoavy rein that cecurred op NECT... “os. good reason to cmtieipate that the eurrent cetailed complex method will yield a better aimlified technique Yor this m, there is little justification for s acre on the at if o i f R if the resultant surface concentrations were multiplied by 100, they well with the dose rate, in rcoentgms per hour, neasured the ehot. This factor was used in making up Table 2, and it ve fairly zood results for Bu.vO, MOMEO, end UNIGN clso, to ie some to oversestimte the lower dose ratos at distances. In Table 1, however, it is clear that the azroencnt tine.