O'Reilly — On the Dates of Volcanic Eruptions. 405 



the i/ear, his tables as given supporting strongly his conclusion that 

 eruptions in high latitudes are much more frequent in summer than in 

 winter. His paper or essay on Synchronism and Antagonism, pub- 

 lished in 1863, and of which details have been hereinbefore given, 

 brings into connection the years of eruptions and the sim-spot period, 

 and in this respect is based on "Wolf's list of sun-spot maxima and 

 minima years (published in a complete form in 1870). The same 

 remark holds good as regards Poey's last paper. Wolfs list is there- 

 fore the important element in both cases taken in connection with their 

 lists of eruptions, hurricanes, and earthquakes. It is to a certain ex- 

 tent remarkable that this list of sun-spot periods has not, as yet, 

 received any recognition on the part of geologists, as if there were no 

 admissible connection between the phenomena taking place at the 

 surface of the sun and those taking place on the surface of the earth. 

 And yet it can be shown by hundreds of cases mentioned in Mallet's 

 and Perrey's lists of earthquakes that between eruptions, earthquakes, 

 magnetic disturbances and phenomena, and atmospheric perturbations, 

 a close, if not intimate, connection exists, and, consequently, if any 

 one of these sets of phenomena show a distinct relation with the sun- 

 spot period, the others should likewise do so to a greater or less ex- 

 tent. JlTow, the cyclones and hurricanes of the Indian Ocean, as also 

 the monsoons, on the regular advent and course of which the good 

 and bad seasons of India and South Africa depend, have been carefully 

 studied, and shown to have a relation with the sun-spot period. ^ 

 W. Stanley Jevons, writing on the "Series of Decennial Crises" in 

 Nature, vol. xix., p. 34, says : — 



" I can entertain no doubt whatever that the principal commer- 

 cial crises do fall in a series having the average period of about 10-466 

 years, moreover, the almost perfect coincidence of this period with 

 Brown's estimate of the sun-spot period (10'54) is by itself strong- 

 conclusive evidence that the phenomena are causally concerned. The 

 exact nature of the connection cannot at present be established." 



D. E. Hutchins, Conservator of Forests, Knysna, S. Africa, pub- 

 lished in 1889 a series of lectures on "Cycles of Drought and Good 

 Seasons in S. Africa," bringing into close relation the seasons of 

 that country and the sun-spot period, and considering it as funda- 

 mental for the sound agricultural administration of the regions re- 

 ferred to. At p. 109, the author gives a forecast table of the 

 seasons to be expected for the years from 1888 to 1920, which gives 



1 See Meldi-um, Nature, 9tli Oct., 1873. 



