Great North American Lakes. 83 
dred feet—as at Chepstow on the Severn, at St. Malo on the 
coast of France, and at Annapolis in the Bay of Fundy. 
To obtain full and exact data as to the rise and fall of 
the water in Lakes Ontario, Erie, Huron, Michigan, and Su- 
perior, it is requisite that nilometers should be placed at a 
number of points, on the shores of each, both in their nar- 
rowest and broadest dimensions, and the changes carefully 
observed, during a whole year, or at least, for several monthis ; 
and accurate tables kept, of the times and extent of each 
flux and reflux, in which, the position, as respects the merid- 
ian, and the phases of the moon, and also the course of the 
winds should be noted. This could be most conveniently 
done by the gentlemen of the army, who are stationed at 
the various military posts, situated on the lakes. To them 
we are indebted for nearly all the information, we sess on 
this interesting subject ; and it is desirable, that they should 
merit, still higher distinction, and gratitude, by furnishing an 
ample supply of facts, on all the objects connected with, and 
calculated to illustrate a phenomenon, so little known, and 
so imperfectly explained 
As to the periodical increase and diminution of the whole 
volume of water in the lakes, I am not in possession of any 
definite facts, save those contained in Capt. Dearborn’s let- 
ter, and in the following extract from the New York Mer- 
cantile Advertiser. 
“ A gentleman, just returned from a tour to the west, in- 
Pinel dha editor, that the waters of Lakes Ontario, and 
Erie, are, at present, nearly two feet higher, whilst those of 
Superior, are considerably lower, than ever before 
known.” 
through Lakes Huron and Michigan, a P accion of the 
North West and Michigan Territories, during the year 
“ While at Green Bay I made observations. on the ebb 
and flow of a lake tide. The existence of tnis phenomenon 
has been known for nearly a century and a half,* and yet 
has occasioned no thought nor investigation. Even Volney 
has allowed it to pass without a theory! At eleven o'clock, 
* Fra. Marguette mentions this tide in 1673. 
