O'Reilly — On the Bates of Volcanic Eniptions. 419 



Of the total number of eruptions here recorded 43°/^ come •n'ithin 

 the period covered by Wolf's tables of sunspot period. Taking the 

 dates from the more recent backwards we have the following table of 

 relative correspondence between the dates and the maxima and minima 

 of the sun-spot period. : — 







Sun-spot 









Sun-spot 





Erup- 



Dates. 



years. 



Differ- 



Erup- 



Dates. 



years. 



Differ- 



tions. 





Wolf's list. 



ence. 



tions. 





Wolf's list. 



ence. 



76 



1878-40 



-1879 



0-6 



53 



1766 



-1766-5 



0-5 



75 



1865 



- 1867-2 



2-2 



52 



1763 



+ 1761-5 



1-5 



74 



1864 



H- 1860-2 



3-8 



51 



1759 







73 



1851-65 



-t- 1848-6 



3-05 



50 



1757-84 1 

 1754-16 j 



- 1755-5 



0-5 



71 



1842 



- 1844 



2 



49 



70 



1838 



-h 1837-2 



0-8 



48 



1747 







69 



1832 



- 1833-8 



1-8 



47 



1744 



- 1745 



1 



68 



1831 



+ 1829-5 



1-5 



46 



1735 



-1734 



1 



67 



1819 



+ 1816-1 



2-9 



45 



1732 







66 



1811 



- 1810-5 



0-5 



44 



1723 



- 1723-5 



0-5 



65 



1808-16 1 

 1808 1 







43 



1701-16 



+ 1705-5 



4-34 



64 







42 



1693-16 1 

 1692-04) 



-f 1693- 



0-16 



63 



1805 



+ 1804 



1 



41 







62 



1802 







40 



1688 



- 1689-5 



1-5 



61 



1800 







39 



1082 



+ 1685 



3 



60 



1799 ) 







38 



1668-1 



- 1666-9 



1-2 



69 



1798 



-1798-5 



0-5 



37 



1646 



-1645 



1 



58 



1797 ) 







36 



1632-09 



-1634 



1-91 



57 



1792 



-1-1789 



3 



35 



1619 



- 1619 



0-00 



56 



1787 



-1784-8 



2-2 



34 



1614 



-)- 1615-5 



1-5 



55 



1781 







33 



1610 



- 1610-8 



0-8 



54 



1779-38 



-1- 1779-5 



0-12 











The mean difference between the dates as given, and the sun- 

 spot years of Wolf's list is 1'56, which under the circumstances must 

 be allowed to be a close correspondence, and to go far to justify the 

 views put forward by Kluge in this respect. It is also reasonable to 

 assume that for the dates prior to 1610-8, the differences between the 

 sun-spot years and the eruption years would have been found to 

 correspond equally closely, did we possess data relative to the 

 maxima and minima sun-spot years going back sufficiently far. It 

 is very interesting to note that while there are 18 minima years 

 indicated, there are but 13 maxima years; and it further appears, 

 that taking the mean of the differences between the eruption dates 

 and the corresponding sun-spot dates in both cases, the mean 

 difference in the cases of the minima years is only 1"09, while in the 

 case of the maxima years, it is 2-05, from which might be drawn the 



