Final Preparations for Rehearsals and Test

During the period from June 9 to June 30, the test date was set for July 13 with a first rehearsal July 8. This fixed the schedules for everyone participating in the Trinity test. S. K. Allison as chairman of the Cowpuncher Committee had the responsibility of integrating the efforts of the entire Project Y and the receipt of material from Hanford.

On June 30 a review was made of all schedules at the Cowpuncher Committee meeting where all division leaders submitted the earliest possible date at which their work could be ready. The earliest date for the Trinity shot was changed to July 16...

[On July 16,] The arming party remained at the base of the tower until just before 5:00 a.m. when the weather reports from Hubbard by phone began to look satisfactory for a shot. Sgt. Stewart was released to S-10 000 before 5:00 a.m.; his job had been completed. The drive out to S-10 000 was not made above 35 mph, contrary to rumors. Original plans were for the entire party to return at 2:00 a.m. to S-10 000 where J. R. Oppenheimer, Gen. Farrell, J. M. Hubbard, and K. T. Bainbridge would decide at t₀-1/2 h whether or not the test should be run. One dissenting vote was sufficient to call off the shot. Sunday afternoon discussions of possible sabotage of the bomb made it reasonable for the arming party to guard the tower until the last possible moment.

The final OK for the 5:30 a.m. shot was given at 5:10 a.m. because 20 min were needed for preparation in the three main shelters.

Source: K. T. Bainbridge, Trinity, Los Alamos Scientific Laboratory, May 1976, LA-6300-H, National Technical Information Service