294 EARTHQUAKES. 



conclusion would partially accord with the third barome- 

 trical law, or the fact that there are more occasions on 

 which we get a low barometer during the winter months. 



Other writers who have examined this question are 

 Volger, Kluge, Andres, and Poly. The latter investigator 

 sought a connection between earthquakes and revolving 

 storms, in the centres of which there is usually an ab- 

 normal decrease of atmospheric pressure. If an area over 

 which such a sudden change in pressure took place was 

 in a critical state, it is not difficult to see that storms 

 such as Poly refers to might sometimes be accompanied 

 by earthquakes. 



Fluctuations in temperature, — Inasmuch as fluctua- 

 tions in temperature are governed by the sun, it may at 

 once be said that there is a connection between earth- 

 quakes and readings of the thermometer. Certainly 

 earthquakes occur mostly during the cold months or 

 in winter. Similarly, as changes in temperature are so 

 closely connected with barometric fluctuations, and these 

 are said to have a direct influence upon the yielding of 

 the earth's crust, seismic phenomena are indirectly linked 

 to fluctuations in temperature. A rise in temperature is 

 usually accompanied by a fall in the barometer, and this 

 in turn may be a condition favourable for the occurrence 

 of an earthquake. 



If we regard solar heat as an agent causing expansions 

 or contractions in the earth's crust, then fluctuations in 

 temperature become an immediate cause of earthquakes. 

 The probability, however, is that solar heat has little or 

 no connection with the final cause producing earthquakes, 

 although at the same time coincidences between the 

 occurrence of earthquakes and unusual fluctuations in 

 temperature may from time to time be observed. 



Winds and earthquakes, — Although it may be 



