JS.^QHES 0.V THE I.AKE OF GENEVA. 203 



tate thedifferent atmofpheric columns, though very near each 



ttiier, may Some of them be agitated and others cairn. This 



appearance of the furface of the lake is cortfidered by the 



fifhermett as a fign of rain. 



Tne fecond phenomenon of which Mr. Vaucher fpeaks, Another phc- 



confitts in certain fonorous diftant explotions or noifes which "omenon refcm- 



1 , . bling the diftant 



refemble thofe of the ditcharge of artillery, and are Sometimes no -,f e f ^1. 



heard in the fine fummer evenings. This phenomenon is rare, toy 

 but is neverthelefs affirmed by feveral inhabitants near the lake 

 of Geneva. It alto takes place in the lake of Zurich accord- 

 ing to Mr. Efcher, and in that of Baikal according to that of 

 Mr. Patrin. Mr. Etcher afferts that half or three quarters of 

 a minute after having heard one of thefe noifes he faw a bubble 

 of air about a foot in diameter rife out of the lake of Zurich. 



, .: .,„. ,'-..^ ;,;..,. , Annotations. — *W. N. , ';, • - : •:**?-. 



It does, not feem to me that any of the caufes yet pointed-out Objeaions to th» 

 are fufficient to account for the erred of the feiches. Sudden theories which 

 •or ftrong blalls of wind could Scarcely operate in this way fo ed refpccling the 

 partially as that the exigence of fuch Squalls mould not at the feiches, 

 jame time have fixed the attention of the common people as 

 Well as of the more accurate obfervers who have noticed thefe 

 changes. It is perhaps equally difficult to fuppofe fuch un- 

 heeded variations totakeplace in the Arve fufficient to account 

 tor thefe very remarkable changes in the lake. Mr. BertrandV 

 electrical hypothesis refers us to a clafs of appearances too little 

 underwood to be admitted^ otherwife than in the way of loofe 

 •conjecture ; befides which, it mult be remarked that the agency 

 of electrical clouds is much more generally directed to moun- 

 tains than to the valleys in which lakes muft necelTarily have 

 .their Situation. Much ingenuity is laltly (hewn by Mr. Vaucher —particularly 



in his explanation, which neverthelefs requires us to admit of „ °, , r * 

 1 •..«*,■• Vaucher s of 



atmofpheric columns considerably differing in weight and oc- atmofpheric 



cupying very fmall extent of furface. If this be even admit- P reffuve * 



ted as poffible, yet Strong doubts may furely be entertained as 



to its probability. It appears to me that the object in queftion 



.admits of an eafy folution upon other principles, and alfo that 



his explanation is grounded on positions not confident with the 



known laws of Statics. 



This ingenious author alTumes as the conditions of his ge- Recapitulation 



ncral theory that the lake Should coniift of two portions of °f *'» fads aI * d 



r deduct ions# 



water, 



