Great North American Lakes. 83 



dred feet — as at Chepstow on the Severn, at St. Male on the 

 coast of France, and at Annapohs 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 months ; 

 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 possess 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- 

 formed the editor, that the waters of Lakes Ontario, and 

 Erie, are, at present, nearly two feet higher, whilst those of 

 Lake Superior, are considerably lower, than ever before 

 known." 



Extract from a printed report, made to Maj. Gen. Brown, 

 commander in chief of the army, of a tour, from Detroit, 

 through Lakes Huron and Michigan, a portion of the 

 North West and Michigan Territories, during the year 

 1817, by Maj. Samuel A. Storrow, late judge advocate. 



" While at Green Bay I made observations on the ebb 

 and flow of a lake tide. The existence of this 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. 



