AFRICAN SWAMPS SIR, , —Professor Frank Debenham in his interesting article,
African Swamps, mentions the fact of the cyclical flooding of swamps. It may be of interest to Professor Debenham and your readers to know that there are reasons to think-that such cyclical flooding is correlated to the eleven year sun-spot cycle, as has been mentioned on several occasions by the late Sir James Jeans and Doctor H. T. Stetson of the U.S.A. I have personally investigated the question of the variation in the height of the level of Victoria Nyanza covering the period between 1896-1927, the only figures I could find, and have discovered that not only does this water- level follow the sun-spot cycle but an analysis of the two graphs gives a correlation coefficient as high as 0.658 ± 0.067. The reason for this is that the sun-spot cycle affects the weather. A similar relation has been found by American observers in the case of some of the American and Canadian lakes, and this, perhaps, will answer Professor Debenham's question. As regards the remedy for smelt flooding, it is obvious that, since we cannot control solar activity, we .cannot control its effects, but, with the aid of existing graphs, it is. possible to predict, roughly, when such flooding
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