NEW STEP BY STEP MAP FOR UNDERWATER NUCLEAR TEST 'UMBRELLA' (1958)

With test moratoriums on the horizon, American weapons labs rushed out several new layouts. A hard deadline for testing was established at midnight (0000 hrs), 31 Oct 1958, as negotiations had been established to begin that working day, and the schedule displays it, with 29 tests executed in October, 4 of these on the last working day. A single oth