A model of the magnetospheric substorm
IT is generally recognised that the Earth's magnetic tail and the plasma sheet play a vital role in the processes responsible for the observational phenomenon known as the magnetospheric substorm. Many different models1–5 of substorm behaviour have been described with differing degrees of success, and to propose another requires some justification. A new model, if it is to be useful, must do two things. It must be specific enough to make quantitative theoretical analysis possible, and it must fit the morphological features more completely or in a more elegant way than other models. In addition, it should be distinctive enough from other models to be separated from them by observational tests. I believe the model presented here has those properties.
Plasma-sheet structure and the onset of magnetospheric substorms
Abstract A model is presented in which the plasma sheet is not confined by a closed magneticfield configuration. Instead, the plasma-sheet particles continually leak down the tail along open field lines; the loss rate is controlled by particle scattering with magnetic-field irregularities and waves, and the length of the plasma sheet is determined by loss of plasma-sheet particles to the neutral sheet. The escaping particles are replaced by continuous injection of magnetosheath plasma entering the magnetosphere through the demarcation lines on the dayside magnetopause. According to the model, plasma-sheet particle fluxes at the lunar distance in the tail should normally be less than fluxes observed at the Vela orbital distance by a factor of two or more. The substorm onset in this model is the result of a depletion of the near-Earth plasma sheet owing to enhanced downstream escape. Thus the plasma-sheet ‘drop-out’ observed at the Vela distance should be accompanied by a temporary enhancement of plasma-sheet flux at the lunar distance. Rapid magnetic merging then proceeds in the near-Earth neutral sheet by a simple ‘vacuum merging’ process until the merging is slowed by the reappearance of the plasma sheet near the peak of the substorm.
The Austro-Prussian War: Austria's War with Prussia and Italy in 1866 . By Geoffrey Wawro. Cambridge: Cambridge University Press. 1966. Pp. 313. $59.95. ISBN 0-521-56059-4.
This expanded and reworked Yale dissertation ventures into a topic done spellbindingly two decades ago by one of the grand masters of German military affairs, Gordon Craig, whose Battle of Koeniggraetz (Philadelphia: J. B. Lippincott, 1964), was published in a series commissioned by Hanson W. Baldwin. NewYork Times military affairs editor. Wawro does not approach the literary brilliance of Craig, but his work goes beyond it in several important respects. First, although Craig dealt with a good deal of the preliminary background and also the aftermath, his book focused squarely on the major battle which decided the war, whereas the book at hand deals with the entire war, which included several other battles, notably Langensalza, between Prussia and the Hanoverians in north-central Germany and Custoza between Austria and Italy in northern Italy. Secondly, whereas Craig knew the German sources as well as anyone, Wawro here uses not only German, but Austrian, French, British, and Italian ones. Of the last two, the former are important for the diplomatic background, the latter for the southern campaign area as well as for the problematic PrussianItalian relations. Thirdly,Wawro has dug deeper than Craig into primary source archives. Especially for the central emphasis of the book, the Austrians and Italians, he has mined the archives in Vienna, Rome, Naples, Milan, and Venice. For example, he uses a number of war diaries which officers from captain to field marshal kept and later deposited in military archives. Interestingly, both authors use Hans Delbriick andTheodor Fontane. Delbriick wrote half a dozen essays on the war and after his death in 1929 two of his colleagues published a fifth volume of his classic Art of War in the Framework of Political History which dealt substantially with 1866, partly on the basis of Delbriick's Berlin University lecture notes. Fontane covered the war as a newspaper correspondent and published more than a thousand pages from his eyewitness experiences, Der deutsche Krieg von 1866, 2 vols, (Berlin, 1871-72).