290 On the Seiches of the Lake of Geneva. 



uncommonly dry and free from storms. And as it is well known 

 that this settled state of the atmosphere is that in which the 

 seiches are the least considerable, the author had not an oppor- 

 tunity of observing any in which the oscillation was greater than 

 a foot. 



The exact mode in which this rise and fall takes place merits 

 observation. It is more of a swelling up than any thing else, 

 without any agitation or any thing stormy : where the lake 

 communicates with any neighbouring pool, as for example in the 

 various ditches which surround the fortifications of the town, 

 the waters in these latter neither rise nor fall cotemporaneously 

 with the other, but they flow uniformly from the lake to the 

 ditch, or from the ditch to the lake, according as the waters of 

 the latter are rising or falling. 



It may be remarked in passing, that a very erroneous idea 

 would be entertained of the phenomenon, were it conceived to 

 be owing to any transportation of the water from the large lake 

 into the contiguous pools ; for, as we have already said, the 

 water being often in a state of perfect repose during the occur- 

 rence of the largest seiche, it would be impossible, according to 

 this explanation, to assign a reason for the many momentary 

 variations, and especially to conceive how the seiches should not 

 accurately correspond, and manifest themselves at the same mo- 

 ment upon the opposite banks; and, finally, how the transport 

 of so much water could be effected without shewing itself in 

 some rapid current, flowing from the greater mass of waters in- 

 to the smaller, or the reverse. 



It was not enough, continues Mr Vaucher, for the accom- 

 plishment of the task, to learn only the principal circumstances 

 connected with the seiches at the western extremity of the lake ; 

 it was of importance to ascertain also what happened at the other 

 extremity, that we might either confute or confirm the various 

 explanations which had been given of the phenomenon, and 

 finally to arrive at a discovery of the true cause. 



I applied then to an inhabitant of Vevey, who had the kind- 

 ness, whenever his time permitted him, to make those observa- 

 tions which I requested. But he was never able to perceive a 

 sudden variation of the level of the waters of the lake to a 

 greater extent than a few lines. This result surprised me the 



