US Silde Ruler 'Earl L. Long' Manhattan Project

In a very nice condition a US Silde Ruler Post 1444KIt says on the back of the ruler 'Made in Occupied Japan' which was the years between 1945 and 1951.Attached inside is a note that the ruler was from Earl L. Long, member of the Manhattan Project.Earl L. Long was a leader within the Manhattan Project, specifically heading Group X-5 (Detonating Circuit), a crucial engineering group established in March 1945 to develop the bomb's firing mechanisms, working on the complex electronic systems for detonation, a significant technical role in bringing the atomic bomb to fruition.