﻿324 Ca7iadian Retorcl of Science. 



which although falling short of the destructive class, was- 

 probably amongst the most severe which have visited this 

 portion of Canada in recent years, was recorded at 

 Montreal and throughout Quebec Province and Eastern 

 Ontario. The disturbance covered an area measuring 

 approximately 300 miles by 100 miles, having its major 

 axis along the St. Lawrence Valley and the Island of 

 Montreal at its centre. On the 25th of March a 

 shock was recorded at Esquimalt. On the 26th 

 Montreal and parts of Quebec and Eastern Ontario 

 were again visited by a slight but sharply dis- 

 tinct earthquake. The main shock occurred at Oh. 

 4m. 20s., Eastern standard time, at McGill College, being 

 preceded and followed by a distinct tremor of buildings 

 with the usual rumbling noise. The tremor was first 

 observed at 5 seconds before the main shock, and lasted 

 for about 10 seconds after it. This earthquake is a 

 somewhat exceptional one in Canadian records, as it 

 seems to liave been heralded by a slight tremor at about 

 midnight, and to have been followed by another similar 

 tremor at about 5 o'clock a.m. 



The earthquake of March, the 23rd, is of interest 

 locally, not only on account of its severity, but also as it 

 was the first of which a record was obtained in Canada. 



A set of Ewing Seismographs had recently been set up 

 in the Physics Building which, although frequently 

 deranged by the engineering operations in the vicinity, 

 fortunately happened at the time to be in adjustment and 

 on the look out for a chance earthquake. 



The object of these instruments is to record the actual 

 extent, direction and velocity of the movement of the 

 ground at any time during the shock. It has been 

 abundantly shown of the researches of Ewing and others, 

 especially in Japan, that no adequate record can be 

 obtained by any of the older methods, which, at best, give 

 only the direction or amplitude of the principal movement, 



