O'Reilly — On the Datea of Volcanic J^riiptions. 421 



The weather of 1593-5 was remarkable on account of the severity of 

 the winter on the Continent and in Great Britain. Arago's work 

 gives the following detail (pp. 275-6) : " A Paris cethiverdura depuis 

 le 20 Deer. 1564, jusqu'au 24 Mars 1565. La gelee dura d Liege 

 du 14 Nov. 1564, a la fin d'Avril 1565. On tint boutique sur la 

 glace dont etait convert I'Escant. En Decembre la Tamise fut prise au 

 point qu'on la traversait sur la glace. En provence le Rhone fut 

 pris dans toute sa largeur a Aries et les oliviers perirent." 



The year (1536-33) gives with the maximum year + 1615*5, an 

 interval of 79' 17 years, which compares well with the actual inter- 

 val - 1889-6, and - 1810-5 = 79-1, and even with the normal interval 

 77-7, the difference being only 1-47. It may therefore be taken as a 

 maximum sun-spot year. There is no record as to the winter of this 

 year in the records already referred to. 



The interval between 1536-33 and 1447 is 89-33 years. This 

 differs from the normal interval - 88-8 by 0-53 only. On the 

 other hand we have the actual interval - 1889-6 -(+ 1727-5) = 162-1, 

 and for 1447. - 1610-8 - 1447 = 163-8, showing a difference in this 

 case of 1 -7. There is no record of the weather of this year in the works 

 already cited, and there is nothing to indicate whether the years 

 should be looked on as a maximum or a minimum, except the regularity 

 of the interval, which would point to its being taken as a maximum. 



The interval between 1444 and 1447 is 3 years, that is about 

 the usual time from a minimum year to the next maximum. A nearly 

 same interval has sometimes occurred between a maximum and a 

 minimum + 1615-5 and (- 1619) = 3-5. This year makes with -1610*8, 

 an interval of 1 66-8 years, which only differs from the normal interval, 

 166-5, by 0-3, so that it may be taken as a minimum sun-spot year. 

 The weather record for the year in the Annals of Ulster, is "A wet 

 summer and harvest, with all corn maltish for the most part " 

 (Mc.Firbis' Annals), which, so far as it goes, would point to a 

 minimum. 



The interval between 1408 and 1444 is 36 years, which differs 

 from the normal interval by 2*7 years. However the interval between 

 1408 and 1536-33, which was taken as a maximum year, is 128-33 

 years, which agrees well with the actual interval - 1889-6 - (+ 1761-5) 

 = 128' 1, and which might be taken as pointing to the year in question 

 being considered a maximum. The weather record is given in Arago's 

 work as follows (p. 269, 270) :— " L'hiver de 1408 qui sevit sur le 

 ISTord de I'Europe et jusqu'aux bords du Danube fut le plus cruel qui 

 eut ete depuis 500 ans. II fut si long qu'il dura depuis le St. Martin 



