No. 6.] DAWSON — FLUCTUATIONS OF LAKES. 315 



last thirty years, which may be connected with the Wolfian Cycle 

 of fifty-six years in the development of sun-spots, The lakes do 

 not seem to have responded to the maximum of 1848, but by a 

 reference to the curve of area of sun-spots, it will be seen that 

 the intensity of this period was not so great as of those on either 

 side of it, and the period of maximum was maintained for a very 

 short time only. The important sun-spot maximum of 1859-60 

 was evident in its effect on the lakes even at their present general 

 high level. With regard to the Lake of the Woods the data are 

 slight, but it may be mentioned that this lake is known to have 

 been very low in 1823, and in 1859 to have attained a point 

 which it has never touched since, and which is about 3 feet 

 higher than the present level. The lake is also known to have 

 been for a good many years higher than usual, and at least one 

 well-marked high water took place between 1823 and 1859, 

 which may very probably have been synchronous with that of 

 1838 on the great lakes. This lake derives its water from the 

 western slope of the same Laurentian range which feeds Lake 

 Superior. 



The correspondence between the periods of maxima and 

 minima in solar-spot cycles and in the fluctuation of the great 

 lakes, though by no means absolute, seems to be sufficiently close 

 to open a very interesting field of inquiry, and to show the ex- 

 tension of the meteorological cycle already deduced by Messrs. 

 Meldrum and Lockyer for oceanic areas in the southern hemis- 

 phere, to continental ones in the northern. 



The great lakes in their changes of mean yearly level probably 

 show a very correct average of the rainfall over a large area, and 

 thus indicate the relative amount of evaporation taking place in 

 different seasons. It is to be observed, however, that the actual 

 mean annual outflow of the lakes would be a better criterion, and 

 that from the form of the river valleys giving exit to the waters, 

 this must necessarily increase in a much greater ratio than the 

 measured change of level in the lake itself. It is much to be 

 desired that such observations should be systematically made. 

 The occurrence of seasons of great activity of evaporation and 

 precipitation, as indicated by the lakes synchronously with those 

 of maximum in solar-spot production, would tend to confirm the 

 opinions previously formed as to the coincidence of the latter with 

 periods of greater solar activity. Wolf, as quoted by Chambers, 

 ,states from an examination of the Chronicles of Zurich, " that 



