1907.] 



on Seiches in the Lakes of Scotland. 



659 



this purpose a special instrument was constructed after my design, 

 which we called the Wasfgon Recorder (Fig. 2). It is really a 

 combination of the essential principles of the older limnographs of 

 Plantamour and Sarasin. The string of the index limnograph is 

 replaced by a Chesterman's steel tape, which passes horizontally over 

 two pulleys, between which it drags backwards and forwards a little 

 waggon carefully mounted by means of three wheels, which run two 

 on one and one on another of two parallel rails. The waggon 

 carries an ordinary stylographic pen, so mounted as to wiite on a 

 long strip of paper which is moved horizontally by rollers driven by 

 clockwork. As the motion of the paper is perpendicular to the 

 motion of the pen, caused by the rise and fall of the water, the result 

 is the same as before, only the work and the patience are now trans- 

 ferred from the living observer to the waggon and the clock ; and the 

 record is absolutely continuous. The lantern-slides which I now 

 show you will give an idea how the instrument is mounted by the 



Fig. 3. 



lake side, so as to resist the combined efforts of rain, wind and waves, 

 to make an end of the observations of the limnographer. The 

 precautions taken were by no means unnecessary, for in November, 

 1904, part of the Sarasin limnograph under Mr. Wedderburn's charge 

 on Loch Treig was destroyed during a storm, and there were times 

 during the months of August and September, 1905, when I trembled 

 for the security of our installations. 



The slide which I show you next shows a form of limnograph 

 {Fig. 3) which I devised for investigating the nature of the embroidery 

 on the hmnograms. It consists essentially of a large and very 

 sensitive barograph (Richard statoscope), which is connected with a 

 closed weU placed partly in, partly out of the lake. The rise and fall of 

 the lake level causes a corresponding rise and fall of the water level 

 inside this closed well, thereby increasing and diminishing the air- 

 pressure in the cylinder, into which are fixed the barograph capsules, 

 which are thus compressed and extended like the bellows of a 

 concertina. This compression and extension is transferred by a 



2 u 2 



