On the Tides in the great North American Lakes. 211 



the wind blows strongly up the bay and into its mouth. If a north- 

 erly wind prevail for some days, as it often does, down Lake Mich- 

 igan, although it would, for a time, heap up the waters at the head of 

 Green Bay (which runs nearly parallel with the lake,) while propel- 

 ling a still greater mass towards the head of the lake, yet, the con- 

 sequent depression of the level at the mouth of the bay, would soon 

 cause a refluence of the accumulation at its head, even against the 

 strength of the wind. This accounts for the contrariety of wind 

 and, current during a long storm ; but it does not appear to apply to 

 the diurnal, and even hourly, ebbs and floods which almost constantly 

 succeed each other, whether the wind be blowing or not. A conjec- 

 ture of some plausibility is suggested by inspecting the general course 

 of the winds, as they are noted down in the table. Their prevailing 

 course is up or down the bay, whose direction is about S. S. W. 

 This would naturally have a tendency to roll the surface of the wa- 

 ters into waves, npt very unlike those of the lunar tide, excepting 

 their more frequent succession. These waves, whether refluent, or 

 moving before the wind, in passing through the sinuous channel of 

 the embouchure of Fox River, would be compressed into an increased 

 elevation, and may be supposed to exhibit such intervals of fluctua- 

 tion, as have been so long noticed at that place. 



In speculating on the supposed tides of the North American Lakes, 

 it has been natural to regard the head of Green Bay as the point 

 where they would show themselves in the greatest fullness. The 

 course of planetary attraction, operating on a line from east to west, 

 would begin at the eastern part of Gloucester Bay in Lake Huron, 

 and moving over this lake to the Straits of Mackina, and thence 

 across the foot of Lake Michigan and up Green Bay, would tra- 

 verse a space of from four hundred and fifty to five hundred miles. 

 The configuration of the coasts too, through which the line passes, 

 would appear to lend much extraneous aid, to give whatever wave 

 might be formed an undue elevation ; as, after crossing Lake Huron, 

 it would be compressed into the tunnel, or rather triangular form of 

 that part of the Lake which terminates at Mackina, causing a con- 

 volution, which would naturally send it through the straits into Lake 

 Michigan with added height and impetuosity. Again, when the 

 wave, after traversing the foot of Lake Michigan, still somewhat pre- 

 served in its artificial elevation, by a chain of islands that run almost 

 the whole breadth of this transit, enters Green Bay, the same ten- 

 dency to accumulation must prevail throughout the ascent of that 



