zero, stations ranging from 1,325 to 5,600 yards from ground a result of the anesthesia, Of these, 4 died as Satisfactory burns were obtained for study and biopsy on the animals placed in the five nearest stations. b. stations On GEORGE shot, 22 swine were anesthetized and placed in two at 3,460 and 4,780 yards from ground aero, thesia and inclement weather. Of these, 10 died as a result of anes— The circuits operating the mechanismfor the study of The burns that were obtained were Sa time dependency failed because of moisture. tisfactory for gross and microscopic study and for the demonstration of spectral dependency. c, The equipment used in the burn study functioned satisfactorily; it was shown that the atomic bomb flash burn is caused principally by visible light, less so by infrared, and least of all by ultraviolet. dependency of the burning was less successful. The effort to estimate the time Jt seems quite certain that no burn ing occurs during the first maximum of the thermal emission, With the data obtained, it appears that all the burn is inflicted during the first portion of the second maximum and that burning ceases at about 0.3 to 0.5 seconds after the blast. Since this time interval coincides with the peak of the second maximum and since decrease in illumination does not occur until somewhat later, there is uncertainty regarding the significance of the cutoff. Considerable analysis of other phenomena that occur simultancously is required before the time dzta can be accepted. Good kodachrome photographs of the burns and excellent biopsy material were obtained, which should aid in the precise clinical definition of this type of flash burn, 7. BIOLOGICAL DOSIMETRY a, The principal system of biological dosimetry depends upon the measure- ment of the percent change in the weight of the thymUs and splcen of mice on the 5th day after irradiation. Comparison is made with special controls subjected to iden- tical treatment except for the radiation. The effect of total nuclear radiation was -studied in hemisphere stations with aluminum domes; the effect of total neutron radiation in hemisphere stations with lead domes; and the effect of fast neutrons, in hemisphere stations with lead cadmium domes, for EASY shot, 720; and for GEORGE shot, 360, For DOG shot, 480 mice were exposed; All mice were recovered alive. A comparable number of special control mice were placed in the hemispheres as a part of the dry run for each shot. the expected yield, The mouse thymus-spleen system worked very well with A consistent difference was observed between the film pack dose estimate and the mouse dose estimate, with the estimate from the mouse system always +4 . cad a ae ot