David Greenglass's "sketch of the very atomic bomb itself," as the prosecutor, Irving Saypol, described it to the audience and jury at the trial of Julius and Ethel Rosenberg. This particular drawing, "Exhibit 8," was drawn by Greenglass just before the trial to illustrate the most damning informtion he passed on to Rosenberg—a cross-section of the Nagasaki implosion-style atomic bomb. The "implosion" design shown here—whereby a sphere of plutonium is compressed by explosive lenses—was still classified, but the Atomic Energy Commission agreed to allow it to be declassified in court to help prove their case. At the conclusion of Greenglass's testimony, the Rosenberg's lawyer, Emanuel H. Bloch, moved to have "Exhibit 8" impounded, claiming he was worried about the national security implications for its public release. So the implosion secret was out—and described in national newspapers the next day—but the actual picture shown to reporters was effectively secret, until its release was petitioned in 1966, and it was derided by experts as a "caricature" of an actual blueprint for a bomb.
NARA Northeast Region (New York City), NRAN-118-SDUSATTY-114868-7(11).