od 
On the Tides in the great North, American Lakes. 213 
these influences to act without disturbance from other causes, nice 
tide. But such a halcyon lapse of time is improbable, if not imp: 
sible. And as long as shifting winds, or even breezes, are contin 
ally varying the surface of the waters, they will so interfere with 
these delicate tumefactions caused by the moon, as wholly to disguise 
oroverpowélthem. . 
Reasoning from our knowledge of the great inland waters of the 
} ther hemisphere, we should take it for granted, that the North Amer- 
_ iean Lakes have no sensible tide. The Caspian, Black and Baltic 
seas, are said to have none; and even the Mediterranean is indebted 
tothe sharpsightedness of modern times, for the development of such 
aphenomenon on her wide spread bosom. F 
_ As General Dearborn has thrown out a hint respecting the sup- 
posed tide in Lake Superior, I have obtained a communication from 
H. R. Schoolcraft, Esq. on that subject. His long residence at the _ 
foot of that lake, combined with his enlightened powers of observa~ 
tion, and habitual use of them in the furtherance of scientific objects, 
give much weight to his opinions. Gov. Cass, whose opportunities 
ve been great, not only to see himself, but to collect the opinions 
of others, is satisfied that there is no sensible lunar tides on the lakes. 
3 r «“ Derrort, January 19th, 1831. 
Maj. Henry Wurrinc.—Dear Sir,—The idea of the existence 
ofa tide in our lakes, caused by lunar attraction, appears to have 
originated in those changes in the level of the waters, which are pro- 
duced by atmospheric phenomena. ‘These changes were observed 
at a very early day, and they have continued to be observed, by 
tavellers and by the resident population, down to our own times. 
‘Ne attention you formerly bestowed upon the subject, induces me 
to hope that you will resume your observations, and give the result 
of them to the public, in such a form as may enable others to 
judge of these phenomena, and the particulars wherein they dif- 
fit, as I believe, they do indeed differ, from the ordinary, and 
1 any known appearances of oceanic tide. I know not that your 
wn observations will go the length of these conclusions, or that the 
‘ Conclusions themselves are based on remarks, which can be fully 
Srought aie. But I. will endeaver to put you in possession of 
facts. earing on the subject. 
ou. XXI—No. 2. 28 
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