Iviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [^larch I913, 



During a period of nearly half a century, Forel had accumulated 

 observations ranging over almost every branch of science. This 

 catholic quality is well seen in the titles of his published papers, 

 which exceed 300 in number and include, among other subjects, 

 limnology, glaciology, seismology, meteorology, natural history, 

 archaeology, history, and biography. His chief work, ' Le Leman,' 

 the three volumes of which appeared respectively in 1892, 1896, 

 and 1904, treats of almost every branch of physical science and also 

 biology, history, and political economy. It is impossible to touch 

 riere on more than one or two of the chief results arrived at by 

 Forel in this remarkable work. In his chapter on the ' Origin of 

 the Lake ' he does not accept the view that the lake-basin owes its 

 genesis to glacial excavation, but considers that the greater number 

 •of large Alpine lakes were in existence before the Pliocene Epoch, 

 and were inhabited by faunas similar to those which we find at the 

 present day. He favours, on the whole, the view first suggested by 

 ■Charpentier, and afterwards developed by Heim, that a subsidence 

 occurred during the Pleistocene Epoch which caused a reversed 

 klip in the Alpine valleys, thus giving rise to sub- Alpine lakes. 

 Among other notable results arising from his investigation of lakes 

 was the discovery of a numerous and varied fauna living in the mud 

 even at the greatest depths, not only in the Lake of Geneva, but in 

 the other large Swiss and Italian lakes. To the investigation of 

 •problems connected with lakes he gave the name Limnology, and 

 read a paper on this subject at the 6th International Geographical 

 Congress in London, in 1896. In 1901 he published his admirable 

 ' Handbuch der Seenkunde.' 



One branch of limnology to which Forel contributed largely was 

 the investigation of seiches. By means of a special tide-gauge he 

 was able to show that in the water of the lake rhythmical movements 

 take place, comparable to the movements of a pendulum. He 

 showed that a connexion exists between seiches and the move- 

 ments of the atmosphere, and he was still engaged in speculating 

 on the causes of these phenomena within a few days of his 

 death. 



For the study of the varying colours of lake-water he invented a 

 scale of colours or ' xanthometer ' : this consisted of eleven tubes 

 containing varying mixtures of sulphate of iron and bichromate of 

 potash, by means of which he obtained a series of tints varying 

 from azure-blue, through green, to yellow. 



After the year 1871, and especially between 1880 and 1890, his 

 interest was aroused in questions relating to the structures and 



