18 Tides in the North American Lakes. 
combine and assist each other by publications similar to the 
above, (excepting its errors,) the difficulty of collecting such 
facts would be done away with at once. ‘This Journal appears 
to be the most convenient organ for such publications. When 
tables can be formed showing the elevation, extent, thickness 
and dip of the great formations in the individual States, topo- 
graphical and geological models may be constructed, which shall 
be miniature copies of each. 
Arr. Il.—T%des in the North American Lakes ; by D. Rueeues, 
Ist Lieut. 5th Regt. U.S. Infantry. 
Fatuer Louis Hennepin, during his voyage of discovery in ~ 
1679, observed singular currents and fluctuations in the Straits 
of Michillimackinac, for which he was unable to give satisfactory 
explanations. More recently the subject has attracted the atten- 
tion of scientific observers, without producing satisfactory results. 
The Hon. Lewis Cass, while governor of Michigan Territory, 
caused observations to be made during the months of July and 
August, 1828, at Green Bay, then within the jurisdiction of Mich- 
igan, which have been generally received as conclusive evidence 
of the non-existence of tides in the great North American lakes. 
On examination of the table of the Governor’s observations, in 
1836, I was led to believe that an erroneous view of the subject 
had been entertained throughout the investigation. 
I find the Governor’s tabular statement, published in a small 
volume entitled ‘Historical and Scientific Sketches of Michi- 
gan,” embodied in an able article from the pen of Colonel Henry 
Whiting of the Army, and as I am unable to satisfy myself 
whether the tabular statement has ever appeared in the Journal 
of Science, I have considered it necessary to transcribe it, (see 
table A,) reserving also the liberty of occasional reference to Col. 
Whiting’s communication. 
I now propose to make a preliminary examination of this table, 
with the view of ascertaining the results, premising that satisfac- 
tory precautions were apparently taken to guard against local in- 
equalities and fluctuations. 
Taking as an example, the 16th of July, we find that observa- _ 
tions were made at 6% and 8 o’clock, A. M., and at 1, 4, and 74 
