Letters Sent to Dr. L.F. Curtiss, November 2, 1938

Nov. 2, 1938. Dr. L. F. Curtiss, Bureau of Standards, Washington, D. C. Dear Dr. Curtiss: I think you will be interested in learning of what we discovered on the various floors here last Monday, which un- doubtedly explains to a large extent your difficulty in making satisfactory nessurements of gamma activity. Tie checked all the traps in the drainage lines and found nothing of interest. However, on the sixth floor in the machine shop we discovered three boxes of waste which show an activity of approximately 3 milligrans. None of us here knew of the existence of this serap. According to the statement by the nechanic in charge of the machine shop, our late Mr. Barker stored it there temporarily only a few weoks before he left the office for the Hospital. These boxes were within eight or nine feet of your instrunent whon you attempted to make tests in the paper storage roon on the sixth floor, and the only intervening wall is of thin wood construction. or course, in the laboratory and around the freight elevator, also in the hall, you had a little greater distance, and a heavy permenent constructed hollow tile wall, which undoubtedly gave some scroenage On the tenth floor, even though we thought extrone care had been used in removing all activity, we discovered a package of painted dials on the opening table noar the office and mechanical shop that contained app oximately 1/4 milligran activity. Since your instrument is so delicate, this no doubt had somo influence on your readings in that section of the application roome You will be pleased to know that the luminous material cabinet in the weighing room which was discovered to be radioactive has been replaced with an all-metal cabinet. In addition to the ultra-violet light which we propose to use for detecting any possible dust settlings from the luminous material or any which may attach to the person of the operator, we