A high degree of correlation was found between the thymic weight loss in mice and the dosage of x radiation over the range of 75 to 900 r. Splenic weight loss proved satisfactory as a biological indicator over the range of 150 to 600 r. The response of mice splenic and thymic net weight to the mixed radiation in a thermal neutron columm was found to be qualitatively the same as that seen following exposure to x radiation. The relationship of chromosome breakage frequency to radiation dose in the flowerihg plant Tradescantia (spiderwort) was determined for three experiments designed to simulate anticipated field conditions for atomic explosions. Studies are reported which were made to provide control x-ray dose-mortality data for atomic comparison with field montality data obtained from mice exposed to bomb nuclear radiations. Mean survival times and the pattern of deaths as a function of dose and time are presented and discussed. Lethal dose curves established for 110 to 160 1b swine exposed to 2,000 kvp total-body x radiaation at 2 m indicate that bilateral (one-half the total dose to each lateral aspect) irradiation is more lethal than unilateral (total dose to one lateral aspect) irradiation. The dependence of dose distribution on method of x radiation and wave length, the importance of uniform dose distribution, and the difficulties encountered in obtaining uniform dose distribution in a subject 28 cm thick are discussed. From a study of the effects of exposure of swine to tropical conditions for a period of several hours in metal containers similar to those used for exposure during Operation Greenhouse it was concluded that the confinement did not affect Significantly the response of the animals to irradiation. Lethal dosage determinations and pathological effects of various doses of bilateral total-body x irradiation on dogs are reported. Data indicate that confinement of dogs for several hours in Ai cages under conditions similar to those used at Operation Greenhouse did not affect significantly the response of the animals to irradiation. (C.H.) CHROMOSOMES; BODY; BIOLOGY; ANIMALS; ALUMINUM; Descriptors: MICE LOSSES; LETHAL DOSE; IRRADIATION; FREQUENCY; DOGS; DISTRIBUTION; RADIATION DOSES; PLANTS; PLANNING; NUCLEAR EXPLOSIONS; NEUTRONS; * xX WEIGHT; VESSELS; THYMUS; THICKNESS; SWINE; RADIATION INJURIES; RADIATION Subject Codes (NSA): GENERAL AND MISCELLANEOUS 10/5/163 (Item 163 from file: 187312 NSA-16-011356 109) PART 1. INSTRUMENTATION FOR STRUCTURES PROGRAM. ANNEX 3.4 OF DIRECTOR'S REPORT OF ATOMIC WEAPON TESTS AT ENIWETOK, 1951 SCIENTIFIC Northrop, P.A. Sandia Corp., Albuquerque, N. Mex. Publication Date: Jan. 1951 144 p. Primary Report No.: WT-1 Note: Operation GREENHOUSE Journal Announcement: NSA16 Document Type: Report Language: English ™ Instruments are described which were used to measure the blast effects on the structures during Operation Greenhouse. Measurements made on buildings included air pressure, acceleration, displacement, strain, earth pressure, footing pressure, and time-of-break measurements. In additson Stimascope (sound-time-in-materials), tests, Whittemore strain gage tests, surveying measurements, and natural period of vibration measurements, were made before, and repeated after, the blast. The magnitude of the task limited the type of end measurements to the simplest that would give adequate information. Availability, cost, and ease wlth which gage responses could be remotely recorded on magnetic tape, were also controlling factors in the selection of the instruments used. A list of the equipment, photographs, diagrammatic drawings and wiring circuits, and data from preliminary tests of the equipment are included. (C.H.) Descriptors: AIR; BUILDINGS; CIRCUITS; CONFIGURATION; DEFORMATION; EARTH; ECONOMICS; ELECTRONICS; GAGES; INSTRUMENTS; MEASURED VALUES; PHOTOGRAPHY; PRESSURE; RECORDING SYSTEMS; SHOCK WAVES; SOUND ; TESTING; VELOCITY; VIBRATIONS Subject Codes (NSA): GENERAL AND MISCELLANEOUS 5()(}35 11