Handwritten explication as to how the First Atomic Bomb works and its power, by Enola Gay Weapons Officer Morris Jeppson on a Photo of Hiroshima after the Atomic Blast

Morris Jeppson, Weapons Officer of the Enola Gay, the plane that dropped the first atomic bomb on Hiroshima, he helped develop the fusing system of the A-bomb in Los Alamos and he was the last person to touch the bomb when he armed it on the plane above the target. 11" x 8 1/2" color photo of Hiroshima after the devastation of the atomic bomb. Inscribed with a historical note by Jeppson explaining how this atomic bomb worked and its impact:

"The Little Boy design consisted of a large gun that fired one mass of uranium 235 at another mass of uranium 235, thus creating a supercritical mass. The binding energies within atoms are many orders of magnitude greater than the binding energies of molecules. The nuclear weapon detonated at Hiroshima was about 15 kt, i.e. the equivalent of 15,000 tons of TNT. This note on Sept. 11, 2007. Morris Jeppson - Weapon Test Officer - Enola Gay Mission - 6 Aug 1945."

Little Boy was the code name of the first atomic bomb. It was the first uranium-based detonation ever. As Jeppson explains in his note above, The design used the gun method to explosively force a sub-critical mass of uranium-235 and a solid target spike together into a super-critical mass. This was accomplished by simply shooting one piece of the uranium 235 onto the other. It exploded with a destructive power equivalent to 115 kilotons of TNT and killed approximately 140,000 people including associated effects, in Hiroshima. Excellent condition.