1854.] 



ON THE PERIODICAL RISE AND FALL OP THE LAKES. 



297 



the next American writer on this important subject, namely, 

 General Dearborn, who, in the 16th volume of the American 

 Journal of Science, already referred to, observes that " it is not 

 sufficiently certain that tides may not be produced in the great 

 chain of Lakes, in the same manner as they are in the ocean;" 

 and in proof thereof quotes an elaborate theory of the distin- 

 guished Dr. Young (illustrated by three diagrams) which had at 

 that time been sanctioned by the scientific for more than twenty 

 years, not only presuming the possible existence of such tides, 

 but furnishing the means of demonstrating that such is the fact 

 in deep and broad lakes, and even going so far as, where the 

 area and depth of a lake is known, to give a theorem by which 

 the maximum rise and fall of the waters and the time of its oscil- 

 lation, or in which a tide wave might pass over it, can be ascer- 

 tained.* But the General at the same time admits, with regard 

 to "the periodical increase and diminution of the whole volume 

 of water in the Lakes," that he is in possession of no definite 

 facts, save what was contained in a letter from Captain Dearborn, 

 stating, that whilst stationed at the Sault Ste. Marie, on Lake 

 Superior, he had himself observed for three successive days an 

 ebb and flow of about one-and-a-half feet, in the course of about 

 two-and-a-half hours each ; but that he attributed it to the winds ; 

 and that he supposed that the rise and fall which takes place 

 during periods of from three to seven years, to be possibly the 

 effect of increased depth of water in the Lake, caused by an un- 

 usual amount of snow on its borders and tributary streams, or 

 an uncommon rainy season ; and that it even appeared from an 

 extract from the New York Advertiser, that a gentleman just 

 then (1828) returned from a tour to the West, had informed the 

 editor that the waters of Lakes Ontario and Erie were then 

 nearly a foot higher, while those of Lake Superior were consi- 

 derably lower than ever known. The General was therefore led 

 to suggest that, to obtain full and exact data as to the rise and 

 fall of the different Lakes, tide-guages should be placed at a 

 number of points on the shore of each, both in their narrowest 

 and broadest -dimensions, and the changes carefully observed for 

 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 meridian and the phases of the moon, 

 and also the course of the winds should bo noted ; — a plan which, 

 it will be perceived, is very similar to that proposed by myself 

 in my late paper on the establishment of simultaneous meteoro- 

 logical observations. 



Such continued to be the state of the question, till the insti- 

 tution, by the American States, of those great patriotic works, 

 the Geological Surveys of New York, Ohio, and Michigan, when 

 the subject being taken up by the talented individuals employed 

 in that duty, as far as their other immediate avocations would 

 permit, with that spirit which ever distinguishes the lovers of 

 science, I was enabled to glean many interesting additional 

 particulars from their official reports, though, unfortunately, none 

 sufficiently conclusive to solve the great philosophical problem 

 so long under discussion. Among these I, of course, rank first 

 the eminent American geologist, Professor Hall, from whose ela- 

 borate work, put forth under the enlightened auspices of the 

 State of New York, I extract the following valuable remarks on 

 the elevation and depression of the great Lakes :j- 



" The fluctuating level of the waters of these Lakes has -long 



* See American Journal of Science, Vol. 10th, pp. 78 to 94, and 

 Young's Natural Philosophy, Vol. 1, p. 578, &e. See also pp. 44 and 

 46 of this article. 



f See Hall's Geology of New York, pp. 408 to 410. 



excited attention; and many speculations have been hazarded to 

 account for the phenomenon. The somewhat general belief that 

 the periodical rise and fall in their waters occupy seven years 

 appears not to be founded on authentic observation. Sand bars 

 and beaches, or the inlets of certain bays, are regarded as the 

 landmarks; and these being liable to fluctuation, from accumu- 

 lation and removal, it follows that no hypothesis, founded on 

 such observations, can be of any value. . . It is neverthe- 

 less true that there are important fluctuations in the Lake levels, 

 which are unconnected with the temporary influence of winds. 

 The only rational explanation of these changes yet afforded is 

 that depending on the waste and supply of water. From the 

 immense surface exposed to the sun's rays, it is plain that the 

 amount of water evaporated is immense ; and if by any means 

 the process becomes retarded, the water is elevated. Again, 

 the greater quantity of snow falling during certain seasons has 

 been considered a sufficient reason for explaining the increased 

 elevation of the Lakes. If after such a season a summer follows 

 when there is a small degree of sunshine, the amount of evapo- 

 ration being thus diminished, the Lakes remain at a high point. 

 These causes, though perhaps satisfactory, and without doubt 

 true, at least to a certain extent, do not always appear sufficient 

 to account for the fluctuations which have been noticed. Twenty- 

 five or thirty years ago the beach of Lake Erie was a travelled 

 highway beyond Buffalo; but at this time it would be quite im- 

 possible to travel along the same. . . . 



"From the united testimony of persons residing along the 

 margins of all the Lakes, and from other demonstrative proofs, it 

 appears that for many years previous to 1838, all the Lakes had 

 been rising, that about that lime they attained their maximum, 

 and have since (to 1842) been subsiding. I have no means of 

 determining the time or degree of the minimum depression. 

 Mr. Higgins, the State Topographer of the Geological Survey of 

 Michigan, gives the rise of the Lakes as five feet from 1819 to 

 1838, and regards it as probable that the minimum period con- 

 tinues for a considerable length of time, while the maximum 

 continues only for a yeai'. . . A single individual has informed 

 me that about 1788 or 1790 the Lakes were nearly as high as in 

 1838. ... 



" The annual fluctuations in the level of the Lakes are doubt- 

 less due to~the nature of the seasons, depending on the quantity 

 of rain and snow, and the amount of the evaporation ; but it is 

 not so satisfactorily demonstrated that for a series of twenty years 

 the quantity of rain and snow has increased, or that evaporation 

 has lessened uniformly throughout that period. 



" The effect of winds in producing (daily) temporary eleva- 

 tions and depressions is very remarkable. A strong westerly 

 wind will raise the water in the eastern end of Lake Erie several 

 feet in a few hours, when a much larger quantity is driven down 

 the Niagara; and although so rapid a stream below the Falls, the 

 water frequently rises fifteen or twenty feet during a westerly 

 wind. At the same time the water is diminished at the western 

 extremity of the Lake, and a corresponding depression there 

 takes place. The prevalence of a strong easterly or northerly 

 wind in the same way drives the waters to the western and south- 

 ern parts of the Lake, and a much smaller quantity flows down 

 the Niagara during such period. The same effects take place 

 in a greater or less degree in all the Lakes — the rising at one 

 extremity and the sinking at the other, till the wind subsides, 

 when it resumes its equilibrium, and in so doing presents a beau- 

 tiful exhibition of the long swells which are observed in the 

 ocean after the subsidence of a high wind." 



