What the document says
On September 4, 1945, Lt. Colonel A. V. Peterson wrote to Dr. J. R. Oppenheimer at Box 1663 in Santa Fe, New Mexico. Peterson worked out of the United States Engineer Office of the Manhattan District in Oak Ridge, Tennessee, and signed for the District Engineer as Assistant. The letter does one thing. It tells Oppenheimer where copies of two earlier letters went, so that he could show that distribution on his own file copies.
Both of those letters dealt with critical mass, the amount of fissile material needed to sustain a nuclear chain reaction. One was Oppenheimer's letter to Colonel K. D. Nichols, dated 20 August 1945. The other was a letter from Dr. Teller and Dr. Feynman to Mr. S. M. Evans, dated 16 August 1945. The office reproduced both, marked each reproduction Copy 1, Series B, and sent them to Colonel F. T. Matthias for his information.
Key points
- 01Peterson wrote from the United States Engineer Office, Manhattan District, Oak Ridge, Tennessee, and signed as Assistant for the District Engineer.
- 02The office reproduced Oppenheimer's letter to Colonel K. D. Nichols, dated 20 August 1945.
- 03It also reproduced a letter from Dr. Teller and Dr. Feynman to Mr. S. M. Evans, dated 16 August 1945. Both letters concerned critical mass.
- 04Both reproduced copies were marked Copy 1, Series B and sent to Colonel F. T. Matthias for his information.
- 05Peterson sent the notice so the distribution could be recorded on Oppenheimer's file copies.
- 06A stamp on the page states that the classification was cancelled per a document review in January 1973.
Source: U.S. Department of Energy, OpenNet declassified document archive, OSTI ID 938700. The summary is written from the document’s own text. Old scans can be hard to read, so check the original for anything you plan to cite.