TRANSACTIONS OF SECTION A. 



337 



June to December 1900. The next pronounced maximum is well shown during 

 1906, and another in 1910. 



In fig. 1 the dotted line represents the mean of the twelve years' pendulum 

 results, and is termed the normal for curve E. Attention is drawn to curve E 

 during 1904 respecting its small annual inequality and close proximity to the 

 normal line, and also to the few quakes recorded during that year, while the 

 years when E is furthest from the normal are usually periods of abnormal 

 number of quakes, viz., 1900, 1906, and 1910. 



In order to ascertain if any correspondence existed between colliery explo- 

 sions, seismic frequency, and curve E, the United States Geological Survey 

 kindly furnished me with the dates and distribution of all colliery gas explosions 

 (obtainable) when five or more human lives were lost. 



Crosses represent these in fig. 1, and are placed upon the months in which 

 they occurred, while dots represent some of the great European disasters. 



These appear to occur more frequently during the months, of extreme pen- 

 dulum movements, and particularly at or near to the westerly swings. 



Mean Position of E-Vi Horizontal Pendulum at 



Victoria 8 C. 

 Mean Position of MS Horizontal Pendulum at 



Victoria B.C. 

 Cool Mine Explosions in America in which S 



or more lives were lost 

 Cool Mine Explosions in Europe in which S 



or more lives were lost 



Number of Earthquakes recorded 3t Victoria B.C 

 "Bumps' 3 1 Coal Creek B C 



Fig. 1. 



Attention is drawn to the remarkable absence of explosions in 1904, which 

 is also the year of fewest quakes, also when curve E is nearest to its normal, 

 while in 1909 and 1910 during the remarkable departure of curve E from its 

 normal, the colliery explosions both in America and Europe increased alarm- 

 ingly. 



To carry this study still further the author during the autumn of 1910, 

 and by the permission of his Director, Mr. R. F. Stupart, placed a horizontal 

 pendulum of his own construction in the Western Fuel Company's mine at 

 Nanaimo, V.I., at a depth of 979 feet. This instrument is under the sea and 

 far removed from any working face, and by kind permission of the manager is 

 read gratuitously twice daily. Eight months' curve from this instrument and 

 from the surface instrument at Victoria have been plotted, and although the 

 low level pendulum is liable to error until made self-recording, the correspond- 

 ing Victoria curve, though more disturbed, parallels the former to a great 

 extent. 



1911. z 



