310 THE CANADIAN NATURALIST. [Vol, vU, 



THE FLUCTUATIONS OF THE AMERICAN LAKES 

 AND THE DEVELOPMENT OF SUN-SPOTS. 



By G. M. Dawson, Assoc. R. S. M. 



In the course of an investigation, undertaken in my capacity 

 as Geologist to the B. N. A. Boundary Commission, as to late 

 changes of level in the Lake of the Woods, bearing on the ac- 

 curacy of certain former surveys, I found it desirable to tabulate 

 the better-known fluctuations of the great lakes for a series of 

 years as a term of comparison. The observations of secular 

 change in Lake Erie are the most complete, and these, when 

 plotted out to scale, showed a series of well-marked undulations 

 which suggested the possibility of a connection with the eleven- 

 yearly period of sun-spot maxima. A comparison with Mr. 

 Carrington's diagram of the latter confirmed this idea, and as I 

 do not remember to have seen these phenomena connected pre- 

 viously, I have been induced to draw out the reduction of both 

 curves here presented, and the table of the height of water in 

 the lakes. 



The changes of level eifecting the great lakes are classed as 

 follows by Colonel Whittlesey, who has given much attention to 

 the subject : — 



1. General rise and fall, extending through a period of many 

 years, which may be called the " Secular Variation." 



2. Annual rise and fall within certain limits, the period of 

 which is completed in about twelve months, 



3. A sudden, frequent, but irregular movement varying from 

 a few inches to several feet. This is of two kinds, one due to 

 obvious causes, such as winds and storms; another, described 

 as a slow pendulum-like oscillation, has been somewhat fully dis- 

 cussed by Whittlesey in a paper read before the American As- 

 sociation at its last meeting, and is due probably to barometric 

 changes in the superincumbent atmosphere. 



The first class is the only one directly included in the present 

 inquiry. 



I. — Tahle of Great Lakes. — In Mr. Lockyer's new work on 

 Solar Physics, chap, xxvi., entitled "The Meteorology of the 

 Future," exhibits the parallelism of periods of solar energy, as 

 denoted by the outburst of sun-spots, with the maximum periods 



