658 Professor George Chrystal [May 17, 



The modern history of seiches begins with the researches of Pro- 

 fessor Forel at Morges, in 1869. He, and his friends Plantamour 

 (1877), Sarasin (1879), and others, made a thorough investigation of 

 the seiches of the Swiss lakes. Ebert (1901), Halbfass (19()2), and 

 Endros (1903) have done a similar service for many of the German 

 lakes ; the results of Endros in particular being of great interest and 

 variety. Marinelli (1891), Bettoni (1900), Palazzo"(1904) and Mag- 

 rini (1905) have worked in Italy ; Von Cholnoky in Hungary : 

 Denison, Henry and others in America : Burton, Xakamura and 

 Yoshida in Japan. But the great central authority in the matter is 

 Forel, and the rest of us are merely children, gleaning in the field 

 which he has harvested before us. 



The earliest modern observation of a seiche in Scotland was made 

 in the summer of 1902 by two of the Scottish lake surveyors. Dr. 

 Johnstone and Mr. Parsons, on Loch Treig ; and my own connection 

 with the matter began in February 1903, when, at the request of 

 Sir John Murray, I gave a brief account of the hydrodynamical prin- 

 ciples of the subject, with suggestions to his surveyors regarding the 

 observations they might make on the Scottish lakes. But I speedily 

 caught the seiche madness myself, and have been devoting most of 

 my little leisure to the subject for the last three years.* In particular, 

 in 1905, I organised for the Lake Survey a seiche campaign on Loch 

 Earn, and it is mainly of some of the work done then that I wish to 

 speak to-night. And first, a word or two regarding the instruments 

 which we used, and their installation. 



Limnographic Apparatus used. — One of the simplest and most 

 effective of the instruments for measuring the denivellation of a lake 

 is the Index Limnograph, originally devised by Endros. Here is a 

 specimen (Fig. 1) of the form used by the lake surveyors, Ijattered 

 by much active service in all kinds of weather. The essential parts 

 are the float, and its sheltering well and access tube ; a piece of fly- 

 fishing line, passing from the float over a small pulley to a counter- 

 poise ; and an index, attached to the pulley, which indicates on a scale, 

 that can be made as large as we please, the rotation of the pulley, 

 which is of course directly proportional to the rise or fall of the float. 

 The observer is provided with a piece of squared paper, the horizontal 

 divisions of which represent half minutes, and the vertical divisions 

 the readings on the limnograph scale. An observation is made 

 every half minute, and a corresponding dot made on the recording 

 paper. All that is required is a well- sharpened pencil and patience. 

 The result is a curve such as I show you, which we call a Lim- 

 nogram. 



For many purposes it is desirable to have a continuous record, 

 extending over a considerable time, for both night and day. For 



* See various memoirs in the Proceedings and Transactions of the Koyal 

 Society of Edinburgh. 



