SEICHES AND OTHER OSCILLATIONS 
81 
wind during this development, but it seems to have been too gradual to 
be the effective cause of the seiche. There can be little doubt that the 
true cause was a periodic microbaric disturbance, which is very faintly 
indicated in themicrobarograms taken at Ardtrostanand Lochearnhead. 
The present is one of many examples found in the course of the 
observations which prove that a lake-surface is much more sensitive to 
minor fluctuations of the atmospheric pressure than any barometric 
apparatus hitherto constructed. 
— - •5cm. 
^7 ■ 
r 
7 
I 
1/6 Hr$ 
i/f 
■Sen, 
f(> 
4 //7J 
\ 
1 
10 
\ 
I 
^9 
20 
Fig. 32. 
Many more examples might be produced, but probably the 
above are sufficient to establish that the synchronism of quasi - 
periodic disturbances of the atmospheric pressure with the seiche- 
periods of a lake is a frequent cause of seiches. It is true that the 
resonance experiments which Nature performs in her own rough 
laboratory have not the nice exactitude of those devised and carried 
out in a physical institute. But then it is not the way of Nature to 
flaunt her beauties before the unappreciative, or to press the secret 
principles of her action upon the attention of the unreflecting. 
Laboratory Experiments illustrating the Origin of Seiches 
The method of generating seiches by stirring at the nodes, which 
was described above (p. 41), probably does not correspond to anything 
6 
