FOREWORD In early February, 1961, the Fallout Studies Branch of the Division of Biology and Medicine of the AEC asked Sandia Corporation to host a Symposium on upper atmosphere sampling at their Sandia Laboratory. Invitations were sent by DBM/AEC after the dates of April 11 through 13, Papers were invited. As participants declared themselves, a trial agenda was assembled to assess the cover- age likely for the various subjects of importance. participation. 1961, were chosen for the meeting. Seeming inadequacies led to specific requests for additional The response was most heartening as the final agenda attests. spersed with contributed papers as given topics were treated. Discussion topics were inter- These too are reproduced as edited transcriptions of recordings made at the time. The Proceedings have been divided for publication into Part I (Unclassified) and Part II (Classified). Those persons who attended the Symposium and for whom there exist AEC-approved mail channels will receive both Parts land Il. material, Recipients on TID-4500 distribution normally are eligible to receive only unclassified Individuals or agencies not included in the initial distribution but who are eligible to receive the classified portions of the Proceedings should place their requests through regular channels. Editing of the Proceedings has been held toa minimum. Continuity of the text required use of an outline system to indicate the continuity of the Symposium presentation and panel discussions as shown in the Agenda: hence the assignment of roman numeral-letter designations in the table of contents and textual headings. Readers who attended the Symposium may readily key the system to the Agenda, The reader's attention is called to the omission from the Proceedings of the address by Dr. C. E. Junge, Air Force Cambridge Research Laboratories, entitled Diffusion and Sedimentation of Fine Particles in the High Atmosphere, which appears on the April 11 agenda but which is not listed in the table of contents. Dr. Junge was unable to make the presentation because of his absence in India. Unfortunately, Also omitted from the Proceed- ings is the text of Dr. E. A, Martell's address at the official banquet held April 12. ACKNOWLEDGEMENTS The success of the Symposium stemmed principally from the quality of papers presented and, no less, from the unusually participative attitudes of those in attendance. Our gratitude extends therefore to all who attended. Special acknowledgement is due Dr. E. A. Martell for his thought-provoking banquet address prepared in addition to his formal session paper. Finally, the idea of the Symposium, first momentum given the plans, and continuous encouragement through preparatory and final phases, were the work of Joshua Holland and George Anton. We warmly thank them.