396 Proceedings of the Royal Iriah Academy. 



the cases of normal outbreaks) as the days on which the lava com- 

 menced to flow." (Here he gives tables showing this.) 



For the northern hemisphere there thus appears for the summer 

 half-year, i. e. the months of March to August, 314 eruptions ; and for 

 the winter half-year, 267 eruptions. 



For the southern hemisphere the summer half-year (September to 

 Fehruary), gives 129 eruptions, and the winter haK-year 77. On p. 587 : 

 — "Although the predominance of eruptions in the summer appears in 

 this way very marked, the matter presents, however, a different aspect 

 when the figures are distributed according to zones, and more particu- 

 larly when the extreme volcanic districts, such as Iceland, Kamts- 

 chatka, and the Aleutian Islands, are compared with Chili for 

 example. (He here gives a table showing this distribution.) 



In Iceland the number of eruptions that have taken place in 

 summer is nearly fourfold that of the wdnter eruptions ; and leaving 

 out of count the twelve repetitions of the great eruption of Hekla in 

 the summer of 1766, as also the doubtful eruptions of the extreme 

 north of Norway, which to some extent alters the ratio, nevertheless 

 "the proportion between the two remains as 34 : 13. Still more 

 remarkable is the repetition of the Chilian eruptions (the greater 

 number of which belong to the remarkable years 1822 and 1835), the 

 ratio of which between summer and winter is as 28:2. A circumstance 

 worthy of remark is that all the land-elevations of large zones of 

 country (so far as known to me) in the southern hemisphere have 

 happened in the summer half-year: — Chili, 19th ITovember, 1822; 

 20th February, 1835; November 7th, 1837; and 12th February, 

 1839; New Zealand, 23rd January, 1855; Brimstone Island, 6th 

 September, 1825 ; Key and Pesang Islands in the Indian Archipelago, 

 26th November, 1852 ; Tonga Tabu, 24th December, 1853 ; Artutaki, 

 6th February, 1854. 



"It seems already to result from the fact that this particular 

 mode of distribution of the eruptions only holds good for high 

 latitudes, whilst, as the equator is approached it becomes less and 

 less marked, that it is not a direct cosmical influence which causes it^ 

 but that the eruptions are the direct result of the seasons of the year, 

 of the penetration of warm water, and thawing snow or ice-masses, or 

 the falling of showers of rain. That this opinion receives support 

 from other observations, would seem to result from the undeniable 

 connexion betAveen volcanic eruptions and certain conditions of 

 weather, which more particularly comes out in the case of mud 

 volcanoes, since these have their sources of activity at shallow 



