156 Mr D. Milne on Earthquake- Shocks felt in Great Britain, 



Two facts, then, seem to be established : firsty that a very- 

 unusual quantity of rain fell in the year 1839, and especially 

 during the months of August, September, and October ; and 

 second, that much of this rain must either have sunk down 

 into the interior of the earth, or have reascended into the at- 

 mosphere by rapid evaporation. 



(5.) Several of the observers, whose accounts have been 

 quoted, and especially the Rev. Mr Walker of Comrie, take 

 especial notice of the fogs or mists which prevailed to an un- 

 usual degree in Stratherne, when the earthquake -shocks pre- 

 vailed in October 1839. And this circumstance, unimportant 

 as it may at first sight appear, is interesting, on account of its 

 being a common attendant on earthquakes. 



In proof of this remark, it is only necessary to refer to the 

 remarkable fog which, for some months in 1783, overspread the 

 whole of Europe, and part of Asia and America. " It was 

 " perfectly dry, and did not deposit humidity. During its 

 *' continuance, the electricitj^ of the air was increased, and 

 " there happened a great deal of thunder and lightning. At 

 *' that time, Mount Hecla, in Iceland, was in a state of erup- 

 " tion ; and it is imagined that it had its origin from that 

 *•' source.''* 



It will be perceived from the notices formerly given of the 

 Lisbon earthquakes, and of the series of shocks felt at Chi- 

 chester in 1834, that this phenomenon occurred in such a way 

 as to create particular attention. 



(6.) It is proper to take some notice of the height of the ba- 

 rometer at and preceding the time when the shocks occurred, 

 in order to ascertain whether the atmospherical pressure was 

 greater or less than usual. 



It is unfortunate that, in October 1839, there was not in 

 Comrie or in its neighbourhood, any barometer, regularly ob- 

 served and registered ; a want which has now been supplied 

 by the liberality of the British Association, at whose expense a 

 barometer, thermometer, and rain-gauge, have since been estab- 

 lished at Comrie, and the indications of which are regularly 

 recorded. It so happened, however, that whenever the great 



* Robertson on the Atmosphere, voi. i. p. 229. 



