The experimental study of magnetospheric processes consists of several disci plines or methods, developing in two general directions. The first, internal trend covers the progress in experimental techniques and methods and re search specific to this discipline. The other trend combines with other methods in a mutual attempt at understanding the boiling whirlpool of the disturbed magnetosphere. Investigations of auroral X-rays began after Van Allen's (1957) discovery of hard radiation in the upper atmosphere of the auroral zone, and are based on high latitude balloon observations. Scientific...