From the Preface "In celebrating the two hundred and fiftieth anniversary of the birth of its late Fellow, Benjamin Franklin, the American Academy of Arts and Sciences held a Symposium on Janauary 11, 1956, at which the papers reproduced in this volume were presented and discussed...."Franklin was one of America's first and greatest scientists. His scientific observations and theories are all the more remarkable today in the light of the tremendous scientific advances of the past two centuries. Of the many scientific topics that he considered, none attracted his interest more than electricity and its manifestations in the atmosphere. He observed, and presented theories on, many other atmospheric phenomena, including "northeasters" and the aurora borealis. It was natural to select atmospheric electricity as one of the topics of the symposium. The upper atmosphere was chosen as the second subject, not only in view of Franklin's interest in the aurora, but because he would certainly have been intrigued by the often exotic phenomena of the high atmosphere that have been revealed by recent researchers...."Historians have recorded Franklin's accomplishments in science in proper context with the many and varied activities of his full and fruitful life. In paying tribute to a distinguished colleague, scientists offer their best in the form of their own contributions to science. Thus, the papers in this volume are not historical treatises on Franklin's works and time but rather represent the latest and best current developments and ideas in the fields discussed. Without exception the authors have distinguished themselves in their chosen topics. No pretense is made that the coverage of the subjects is complete; this could have been accomplished only at the cost of superficiality. This is particularly true in the case of the upper atmosphere concerning which many important phenomena, including the aurora borealis, are not mentioned at all. An effort was made here to present the points of view of the physicist and the meteorologist, each of whom looks at this vast area with glasses of a different hue. In an age of specialization we must continually stress the basic unity of all the physical sciences, and this purpose is aided here by a common laboratory, the upper atmosphere."