Tides in the North American Lakes. 19 
P.M. The question at once arises, as to the time of high water. 
Was it high water between 8 and 1 o’clock? Was it low water 
at 1 or 40’clock? We observe that embarrassment meets us at 
the very threshold, and it is therefore unnecessary to quote largely 
from this table, as observations were, in no instance, taken more | 
than six times during twenty four hours. Bearing this fact in 
mind, a bare inspection of the table unfolds its true characteris- 
tics; and were I to adopt it as conclusive evidence, I should be 
led to concur in the opinion of its distinguished author, “ that the 
changes in the elevation of the water are entirely too variable to 
be traced to any regular permanent cause.” 
Reflection satisfied me, however, that an error in this tabular 
statement may have arisen from the absence of rapid consecutive 
observations, which alone enable us to grasp a principle clothed in 
subtle and fluctuating indications. 
The accompanying table B, is the result of observations made 
under my superintendence, during the months of September and 
October, 1836, at Green Bay, Wisconsin Territory, with the view 
of elucidating the subject, and ascertaining, as far as practicable, 
the nature of these fluctuations. 
They were made at Fort Howard, on the left bank of the Fox 
River, and about one mile above the expansion of the river into 
Green Bay. It is to be observed, however, that the river still 
winds some four or five miles through an extensive alluvial de- 
posit, before it is lost in deep water. The river is about half a 
mile wide, and is between fifteen and forty feet in depth. 
The station taken for Gov. Cass’ observations is two miles 
above Fort Howard, on the right bank of the river, and about 
two miles below where the current ceases to be perceptible. 
My observations were made by a vertical rod, protected from 
local inequalities by two perforated concentric enclosures, and 
graduated in inches referring to a zero plain above high-water 
mark. The station was near a sentinel’s post, and under the im- 
mediate and constant supervision of the sergeant of the guard, 
and may therefore, I think, be considered as entirely free from 
any accidental inequalities or irregularities of importance. 
It will be observed, that the general direction of the winds was 
also noted; but as I regard them only as a modifying cause, in- 
creasing or diminishing results according to their direction, I shall 
not comprehend their influence in this discussion, and especially 
as they constitute an element susceptible of future examination. 
