PROCEEDINGS OF THE CANADIAN INSTITUTE. 



6l 



will be seen (Fig. 5) the trace began to rise at midnight of the 2Xst, and continued 

 till noon of the 22nd, when it had risen over five inches ; during this period large 

 undulations of forty-five minutes' interval and from one and a half to two inches in 

 amplitude are very marked. From noon to 4.15 p.m. the water level remained 



FIG. 5, 



Stationary, while the oscillations became more rapid ; then the water commenced to 

 fall quickly, reaching its lowest point, a distance of nine inches, at ^.30 p.m., that 

 is, in five hours and fifteen minutes. From this hour you will observe a decided 

 undulatory curve, not merely due to the small rapid oscillations, but marked large 

 undulations, whose average height from trough to crest equals three inches, with 

 a mean time interval between crests of four hourb and forty-nme mmuies. (Fig. 7.) 

 As previously stated, these appear to be the longitudinal "seiches" for our lake. From 

 a careful study of the lake records from their beginning in July last this phenomenon 

 is not to be found except at a time preceding or during tremendous atmospheric 

 disturbances, similar to those at which we are about to look. In the present case 

 this curious phenomenon lasted for three days, and was the precursor of a heavy 

 northerly gale, which at this time of the year also means intense cold. 



Let us hurriedly look at the weather charts during this period. At 8 p.m. of 

 the 21 st the low area which had given us snow had moved eastward, causing a 

 snowstorm throughout the Maritime Provinces, while another depression lay east 

 of Manitoba. In the far North-west an important high area, or anti-cyclone, had 

 appeared. Qu'Appelle reported 10 degrees below zero and a heavy gale blowing. 

 The water of the lake began to rise at midnight. By 8 a.m. of the 22nd the storm 

 centre was over the State of Michigan, causing a high southerly wind with snow 

 throughout Ontario, while the North-west anti-cyclone had developed and extended 

 eastward, Winnipeg reporting 18 degrees below zero and a gale of forty miles 

 per hour. 



At 8 p.m. of the 22nd the wind was westerly in the lake region, but blowing a 

 heavy gale. At 9.30 p.m. the water had reached its lowest point. At this hour these 

 large undulations, or longitudinal " seiches," appeared, and were noticeable during 

 the following three days. In the North-west the pressure was increasing and the 

 temperature falling, while a heavy north-westerly gale prevailed from Manitoba to 

 the lake region. 



At 8 a.m. of the 23rd a north-westerly gale still was blowing over Ontario, while 

 in the North-west the barometer had risen to over thirty-one inches, and the tem- 

 perature fallen to 40 degrees below zero. 



