The International Geophysical Year
That Sydney Chapman was President of the Special Committee for the IGY (CSAGI) in itself suggests a good deal about his contribution to that unprecedented enterprise. It implies, for example, that he must have been involved in its planning and shaping, in its conduct over the eighteen and then thirty months of its duration, and in its completion. What is perhaps not implied, however, is the depth and extent of his role. To say that I can summarize these aspects of Chapman's IGY activities is somewhat absurd: I can only record a few things from my own point of view as one of many who watched him at work over the years.
Chapman would be the first to insist that the endeavor was the work of many hands, that there was a ripeness of time that favored its success. Yet his own role shines clearly. He was part of the enterprise from its inception on the evening of April 5, 1950, at the home of James Van Allen, when Lloyd V. Berkner suggested a third but more comprehensive Polar Year, and Berkner and he pursued this goal steadfastly until its realization. Chapman shaped that broader notion of the International Geophysical Year, and in some ways his commitment long antedated these events. It could be argued that a sense of history and his own scientific work had long before conditioned and prepared him for the IGY. He was intimately familiar with the Polar Years of 1882-83 and 1932- 33. Thus, in 1926 Chapman used magnetic storm data acquired in the First Polar Year as the basis for his hypothesis on the flow of currents in the upper atmosphere, later developing with Ferraro a theory to explain these current systems. Chapman himself was involved in the planning and conduct of the Second Polar Year, and his papers made use of the data of that program. In 1938, with Vestine, for example, he compared current systems using 1882-83 and 1932-33 data. So Chapman had deep roots in these two antecedents of the IGY, suggesting his sensitivity to history and his awareness of the value of synoptic data, but also attesting to his unflagging personal involvement in research.
The act of presiding over CSAGI is a matter of historical record; the acts of leadership are intangible. They are tied to his own being as scientist and man. Continuously over the years Chapman betrayed with almost every breath his own commitment to the pursuit of knowledge. The excellence and breadth of his own work led to a remarkable rapport with all whom he encountered, whether in private, in a small group, or in an assembly. Put another way, he engendered a scientific confidence in the enterprise by virtue of his own investigations and his own willingness to commit himself fully to the IGY.
Intertwined with his particular nature as a creative scientist, and not to be distinguished from it, is his own being as a man. Here, what is relevant to this characterization is the moral fabric, the moral tone of the man. None who encountered him in the planning of the IGY could miss this tone, and none failed to leave him without a general feeling of trust. Such trust, in turn, reinforced one's scientific confidence in the endeavor, and both worked to enhance the IGY. Others may view matters in another light: I doubt that he himself was aware of these elements, for I am convinced that they operated unconsciously; they were just an integral part of the man. But it was this tone, this moral fabric, coupled to a sense of history, that marked his fundamental and essential contribution to the IGY, and to its progeny---COSPAR, IQSY, WMS, SCAR, and other enterprises---in which his hand still appears, steadfast and helpful.
Perhaps one last factor merits lightly touching: tenacity. Behind his own prolific and sustained scientific output, underlying his moral tone, and cropping out in his regimen of walking, swimming, and cycling, there lies a Lancashire doggedness and persistence, quiet but fixed, that pushed the IGY enterprise through its years of planning, execution, analysis, and synthesis.
National Research Council
National Academy of Sciences