424 



Proceedings of the Royal Irish Academy. 



corresponds with the normal interval ll'l x 188 = 2086"8. This year 

 may, therefore, have been a minimum sun-spot year. 



The tabular record of the eruption of Etna prior to 1610 v^ould 

 stand as in the accompanying table, leaving out of consideration the 

 very early dates, as to the accuracy of which doubt may be held. 



Erup- 



Date. 



Probable sun- 



Erup- 



Date 





Probable sun- 



tions. 





spot date. 



tions. 







spot date. 



1 



7tli century B.C. prob. 





18 



812 A.D. 



Interval. 



- 812 ? 



2 



Time of Pythagoras. 









356-09 







Interval. 





19 



116809 





- 1168-09 ? 



3 



477 B.C. 



-477 B.C.?? 







12-91 







51 





20 



1181 





- 1181 ?? 



4 



426 ,, 



+ 426-9 ?? 







104 







30 





21 



1285 





-1- 1285 ? 



5 



396 „ 









143-45 







256 





22 



1328-45 





+ 1328-45 ? 



6 



140 ,, 









4-55 







6 





23 



1333 





- 1333 ? 



7 



134 ,, 









37-60 







8 





24 



1370-60 





- 1370-6 ? 



8 



126 „ 









37-23 







4 





25 



1407-83 





+ 1407 ? ? 



9 



122 „ 









36-17 







73 





26 



1444 





- 1444 ? 



10 



49 „ 









3 







6 





26ffl 



1447 





+ 1447 ? 



11 



43 „ 



5 





27 



1535-16 1 



88-16 





12 



38 ,, 







1-18 







6 





28 



1536-34) 





4- 1536-34 ? 



13 



32 ,, 









29-50 







72 





29 



1565-84 





- 1565-84 ? 



U 



40 A.D. 









13-16 







32 





30 



1579 





- 1579 ? ? 



15 



72 „ 









24 







181 





31 



1603 





- 1603 ?? 



16 



253 ,, 









4 







167 





32 



1607 





-H 1607 ? 



17 



420 „ 















392 













The eruptions of Yesuvius are better known historically than those 

 of even Etna, and should therefore furnish the most reliable dates to 

 be had on a question of this nature. The number that are recorded 

 within the period covered by Wolf's sun-spot list is relatively great, 

 while the dates prior to 1610 are not so numerous as in the case of 

 Etna, and so far this simplifies the comparison with sun-spot years of 

 maxima and minima. The dates are taken from the article in the 



