PROCEEDINGS OF THE CANADIAN INSTITUTE. I35 



states that at Sydney what have been previously termed earthquake waves are in 

 most cases due to atmospheric disturbances in some yet ill-defined manner, and 

 have a marked twenty-six minute time interval from crest to crest. 



Finally, these undulations are universal to a greater or less extent, as has been 

 proved by a personal study of tidal records obtained from all parts of the world. 



CHIEF POINTS DEDUCED. 



1. That the undulations are due to the direct action of atmospheric waves 

 upon the surface of the water at stations, and not to ground swells due to distant 

 storms or " seiche ' movements, as found upon lakes during atmospheric dis- 

 turbances. 



2. There is a marked relative correspondence in amplitude between the baro- 

 metric and water undulations. 



3. That they often appear during fine settled weather, when the barometer is 

 high over the station but decidedly low to the south-west, frequently when over 

 i,D00 miles distant. 



4. That they increase in amplitude as the storm advances, the maximum usually 

 occurring shortly before and at the time of the shift of wind, which also corres- 

 ponds with the time of heaviest precipitation. This tends to prove that the axis 

 of rotation of important storms is inclined towards the direction of its future 

 course. 



5. That after the storm has passed the station, these undulations rapidly 

 diminish, although a heavy westerly gale may still be blowing, provided the tem- 

 perature to the westward is fairly uniform; should a cold or warm wave be 

 approaching marked undulations appear. 



6. Should a south-west storm move with diminishing energy towards the sta- 

 tion the undulations correspondingly decrease as it approaches. 



7. That the tidal records are most disturbed during winter and least in summer, 

 due to the velocity of the primary poleward current being almost double in winter 

 what it is during the summer months. 



8. The disturbed traces during the summer months chiefly occur shortly before 

 or at the time of showers or thunderstorms, and usually precede warm and cool 

 waves. 



g. Whereas many of our storms are whirling eddies, developing from above 

 downwards, it is hoped a further study of these undulations may throw much light 

 upon their future growth and course, even before the ordinary barometer begins 

 to fall. 



10. Meteorologists throughout the scientific world now realize that for the 

 further advancement of weather forecasting a better knowledge of the upper 

 atmosphere must be obtained. Rapid strides are now being made in this direction 

 by means of kites, balloons and cloud observations. May we not add the study of 

 atmospheric and water waves at the bottom of this aerial ocean, which can be 

 carried on during all conditions of weather by means of sensitive self-recording 

 instruments ?* 



The various traces, termed " hydro-aerographs," obtained from such instru- 

 ments, when more fully understood, will indicate to us certain wonderful forces at 

 work far above, not visually discernible either through the dense lower clouds of 

 an approaching storm or the clear blue sky of a fine winter's day. Also we trust 

 that in the near future the installation of such instruments will become universal, 

 and that Canada will lead in such an undertaking. 



*Fully described in a paper read before the Toronto meeting of the British Association in August, 1S97. 



