120 FeatherstonhaugVs Geological Report. 



nomenon is of daily occurrence ; and this was confirmed to 

 me by an intelligent resident of. the place, who was in the 

 babit of observing it both winter and summer. In the winter, 

 he informed me the ice forms in a solid mass to the bottom 

 near to the shores, whilst in the centre of the river, the water 

 at the flow lifts up the ice, which, when the reflux takes place, 

 cracks, and is swayed down again. The observations which 

 Governor Cass made near the mouth of Fox river in 1828,* 

 show an extreme irregularity in the periods of this rise and 

 fall, and which is totally inconsistent with the regular recur- 

 rences of lunar influence. In the paper referred to, which is 

 from the able pen of Major Whiting, U. S. A., there is a letter 

 from Governor Cass, which explains the phenomenon by a 

 reference to causes as constant and irregular as the phenome- 

 non itself. Green bay is an arm of Lake Michigan, running 

 nearly parallel to it, and about one-fourth of its length. Lake 

 Michigan is about three hundred miles long and fifty broad, 

 holding a straight course somewhat east of north, (parallel to 

 all the characteristic mineral directions of this continent.) 

 Governor Cass supposes that w r hen the northerly winds are 

 packing up the waters at the mouth of Fox river, the wind- 

 tide continues still driving on towards Chicago, at the southern 

 end of Lake Michigan ; the effect of which, by lowering the 

 level at the mouth of Green bay, will cause an ebb from the 

 bay into the lake, which will equally prevail at Fox river, and 

 this even during the existence of the wind that had caused 

 the flow there. This would explain the reason of Charlevoix's 

 surprise at seeing his canoe floating off in the face of the 

 wind. A series of observations made in the neighborhood of 

 Fort Gratiot, at Saginaw bay, at Chicago, and Green bay, 

 noting accurately the contemporaneous state of the winds, and 

 any change of level at Michilimackinac, where the same wind 



* " Remarks on the supposed tides." Silliman, vol. 20, p, 205, 



