Smyth possessed security clearances necessary to visit project sites, access documents and to discuss the work with the research personnel.
 Groves approved Smyth's request to hire another Princeton physicist, Lincoln G. Smith, as a research assistant.
 A letter to the Manhattan Project's senior managers, Kenneth Nichols, Robert Oppenheimer, Ernest Lawrence, Harold Urey, and Franklin Matthias, explained:
The purpose is to give clearly and promptly recognition to those who have worked so long and necessarily so anonymously ... To accomplish his purpose, Dr. Smyth must have rather complete information concerning your phase of the project including access to necessary documents ... [and] information and advice from you and your principal assistants.

Since Smyth still had his commitments at Princeton and Chicago, he could only work on the report part-time.
He wrote the report in his office in Princeton's Palmer Laboratory.
Bars were installed on the windows of Smyth's office and the one adjacent to it.
The hallway door to his office was locked and blocked by a large safe so that the only access was through the adjacent office, where there was an armed guard.
The guards worked in eight-hour shifts, and one was present around the clock.
When Smyth sent papers to Groves in Washington, D.C., they went by military courier.

Smyth sent an outline and rough draft of the report to Groves for approval in August 1944, followed in February 1945 by drafts of the first twelve chapters, leaving only the final chapter to be completed.
Groves and Conant reviewed the drafts, and made several criticisms.
They felt that it was too technical for general readers, did not mention the names of enough participants, and dwelt too much on the activities at the Los Alamos Laboratory.
Groves was particularly anxious that deserving people be mentioned, as he felt that this would lessen the danger of security breaches.
After Smyth made a series of changes in response to this, Groves sent the manuscript to his scientific adviser, Richard Tolman.
Tolman was assisted by two physicists who were working in his office at the National Defense Research Committee as technical aides, Paul C. Fine from the University of Texas, and William Shurcliff from Harvard University.
They had the dual task of editing and censoring the manuscript.


Smyth and Tolman accepted a set of criteria, agreeing that information could be released under the conditions: 
I. (A) That it is important to a reasonable understanding of what had been done on the project as a whole or (B) That it is of true scientific interest and likely to be truly helpful to scientific workers in this country and
II. (
A) That it is already generally known by competent scientists or (B) that it can be deduced or guessed by competent scientists from what is already known, combined with the knowledge that the project was in the overall successful or

III. (
A) That it has no real bearing on the production of atomic bombs or (B) That it could be discovered by a small group (15 of whom not over 5 would be senior men) of competent scientists working in a well-equipped college lab in a year's time or less.


Writing to Oppenheimer in April 1945, Smyth noted that 
All discussion of ordnance work is also to be removed.
There is no objection to including the general statement of the ordnance problem and all the other parts of the problem, but the approaches to solution that have been made will be omitted.
On the other hand, the feeling is that there is no objection to including the nuclear physics.
The General believes that the metallurgical work and a considerable amount of the chemistry work should be excluded on the ground that it would be extremely difficult for the average scientist to carry out any of this work without supplies and material which would not be available to him.
I am not entirely clear how this criterion should be applied, but it probably means the elimination of the metallurgical work on plutonium and at least of some of the chemistry.

Tolman and his assistants finished making their changes in July
Smyth possessed security clearances necessary to visit project sites, access documents and to discuss the work with the research personnel.  Groves approved Smyth's request to hire another Princeton physicist, Lincoln G. Smith, as a research assistant.  A letter to the Manhattan Project's senior managers, Kenneth Nichols, Robert Oppenheimer, Ernest Lawrence, Harold Urey, and Franklin Matthias, explained:
The purpose is to give clearly and promptly recognition to those who have worked so long and necessarily so anonymously ... To accomplish his purpose, Dr. Smyth must have rather complete information concerning your phase of the project including access to necessary documents ... [and] information and advice from you and your principal assistants. 
Since Smyth still had his commitments at Princeton and Chicago, he could only work on the report part-time. He wrote the report in his office in Princeton's Palmer Laboratory. Bars were installed on the windows of Smyth's office and the one adjacent to it. The hallway door to his office was locked and blocked by a large safe so that the only access was through the adjacent office, where there was an armed guard. The guards worked in eight-hour shifts, and one was present around the clock. When Smyth sent papers to Groves in Washington, D.C., they went by military courier.
Smyth sent an outline and rough draft of the report to Groves for approval in August 1944, followed in February 1945 by drafts of the first twelve chapters, leaving only the final chapter to be completed. Groves and Conant reviewed the drafts, and made several criticisms. They felt that it was too technical for general readers, did not mention the names of enough participants, and dwelt too much on the activities at the Los Alamos Laboratory. Groves was particularly anxious that deserving people be mentioned, as he felt that this would lessen the danger of security breaches. After Smyth made a series of changes in response to this, Groves sent the manuscript to his scientific adviser, Richard Tolman. Tolman was assisted by two physicists who were working in his office at the National Defense Research Committee as technical aides, Paul C. Fine from the University of Texas, and William Shurcliff from Harvard University. They had the dual task of editing and censoring the manuscript.

Smyth and Tolman accepted a set of criteria, agreeing that information could be released under the conditions: 
I. (A) That it is important to a reasonable understanding of what had been done on the project as a whole or (B) That it is of true scientific interest and likely to be truly helpful to scientific workers in this country and
II. (A) That it is already generally known by competent scientists or (B) that it can be deduced or guessed by competent scientists from what is already known, combined with the knowledge that the project was in the overall successful or

III. (A) That it has no real bearing on the production of atomic bombs or (B) That it could be discovered by a small group (15 of whom not over 5 would be senior men) of competent scientists working in a well-equipped college lab in a year's time or less. 

Writing to Oppenheimer in April 1945, Smyth noted that 
All discussion of ordnance work is also to be removed. There is no objection to including the general statement of the ordnance problem and all the other parts of the problem, but the approaches to solution that have been made will be omitted. On the other hand, the feeling is that there is no objection to including the nuclear physics. The General believes that the metallurgical work and a considerable amount of the chemistry work should be excluded on the ground that it would be extremely difficult for the average scientist to carry out any of this work without supplies and material which would not be available to him. I am not entirely clear how this criterion should be applied, but it probably means the elimination of the metallurgical work on plutonium and at least of some of the chemistry. 
Tolman and his assistants finished making their changes in July 
Smyth Report