these were data on the functioning of Zippers and included: (1) time from X-unit pulse to a known rate of neutron production and (2) the duration of the neutron pulse at this or a higher rate and the total number of neutrons produced. Coincidental with the Zipper monitoring was a measurement of HE transit time, or time from X-unit pulse to a known point in the period of the nuclear detonation. The Zipper measurements were made on 29 shots with one failure due to unknown causes, was monitored on two shots using detectors supplied by LASL. On two shots for UCRL, simultaneity measurements between the firings of two primaries were successfully made. On two shots data on pin switch closures were telemetered and turned over to the interested people. On a third shot, Quince, the raster oscilloscopes failed; therefore, no pin switch information was obtained. The Zipper information was obtained from 517 oscilloscopes. An experimental early alpha system was tried out on 15 LASL shots with at least partial success. The interpretation of these data is not yet complete. The system operates by telemetry of two narrow pulses corresponding to two known gamma levels or generations. "The time between the pulses divided by the delta is an average alpha for that period. The making of these measurements and interpretation of the data was complicated considerably by their transmission over channels already crowded with other data. The responsibility of Project 34.2 was to apply the device fuze and fire Fd ,in support of the DOD-sponsored very high altitude balloon test, Yucca. This test device consisted of 2 pressurized and hermatically sealed, and fuzed with a radio command system backed up with a baro-controlled timer. The radio command system also supplied signals to actuate the canister deployment,weapon reel out, and emergency cutdown. Cutdown signals were also supplied by the fuze hackup time and two clock timers. Radio command and monitoring of the system was accomplished from a trailer van control station located aboard the USS Boxer. The EG&G timing system was utilized to initiate the arm and fire sequence. After five prooftest flights during Hardtack, the Yucca system was launched on April 28, 1958 at 1125 hr from the flight deck of the USS Boxer at 164°30'E longitude and 11°45'N latitude. At launch plus 8 min, altitude 7000 ft, the five instrument canisters were deployed by radio command, and at launch plus 18 min, 12,000 ft, the Yucca device was reel~deployed by radio command. The balloon-borne system reached a floating altitude of 86,000 ft at launch plus 88 min. Later a delay was requested by TG 7.4. Yucca was detonated by radio command at H-hour prime, 1440 hr, at 12°37'N latitude and 163°01.5'E longitude. The yield for Yucca, estimated from the history of firings, was given by B. E. Watt, LASL, aa: The only major operational problem encountered during the test was caused by radio interference with the fuzing command system. After all unnecessary radio circuits below 300 Mc were closed down, all interference disappeared. The objective of Project 34.3 was to procure, assemble, and check out the devices for the two underwater detonations, Wahoo and Umbrella, sponsored by the DOD. Procurement of the needed parts included the design and purchase of the watertight device cases, the underwater signal cables, and the necessary 53