0021620 for detonations near the surface of land, and _K(x,W) = 0.34 x 10710 for detonations near the surface of the sea. The mass considered in these equations is that of the material removed from the crater. No wind corrections were applied to the data prior to correlation; hence an average wind speed somewhere between 10 and 20 mph is associated with the equation constants. - 4 The mass contour ratio is useful in esteblishingthe fallout mass from fallout contour maps in r/hr et 1 br and in estimating the r/hr at 1 br from the decontamination data given in terms of the mass of particles per unit area remaining after decontamination. The fraction-of-device contour is useful in summing the total activity (or fraction of the weapon) in fallout contour maps in r/hr at 1 hr and in estimating (especially for seawater fallout) the surface density of the radio- active elements (say, atoms/sq ft) for a given r/hr at 1 br. The specific activity of the fallout is simply 2pm, /6.0 x 10°3 K(x,W) moles (of fission products) per mg of fallout. poE/N