10 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vot. VIII. 
was .082, and the change in ten minutes was.o6. I also enclose a tracing 
of the air barometer curve, which shows the change very nicely.” On 
December 6th, 1990, [ enclosed a tracing of the record on Denison’s 
automatic gauge, which corresponds with the tracing sent by Mr. Stupart. 
There was no apparent cause for the extraordinary fluctuation, no notice 
in the newspapers, and the disturbance remains unexplained. I also 
reminded Mr. Stupart of an extraordinary fluctuation on April 24th, 
1878, the difference in level being 33 feet. The particulars were given 
in the paper which I read to the Institute in 1894. Mr. Stupart replied 
that “the record in April, 1878, was .o8 in four minutes. The cause of 
this disturbance, also, has never been explained.” With reference to the 
supposed tidal theory, General Comstock, of the United States Survey, 
remarked: “ The known existence of a lake breeze at Milwaukee during 
the summer months at once suggested itself as a cause for this inequality, 
and on comparing the solar diurnal curve for April and November, 
when the lake breeze should be weak, and that for July and August, 
when the lake breeze should be strongest, with that of the whole season, 
it was found that for the former months the inequality entirely disap- 
pears, while for the latter it is considerably increased, thus justifying the 
supposition that the lake breeze is the cause of the inequality.” On 
such evidence the so-called tidal theory may be dismissed. The sup- 
posed rise and fall of the water level of Lake Ontario, every seven 
years, may also be dismissed. An examination of the harbour profile of 
the water levels will be sufficient to dispose of any such theory, the rise 
and fall being quite irregular, not even corresponding with the rainfall. 
My task is now done, and I shall have to leave future observations to 
others, who, I trust, will do justice to the subject. The records of fluc- 
tuations will be continued, to which reference can be made in the 
Harbour Office at any time. 
