SUNSPOTS AND VOLCANIC AND SEISMIC PHENOMENA. 55 



It is curious that Borneo, so close to Java, is almost free 

 from earthquakes, and does not possess any active vol- 

 canoes, although in early Tertiary times this island was 

 the seat of both. Borneo retains, however, several con- 

 tinental characteristics ; unlike Java it contains palaeozoic 

 rocks covering considerable areas. 1 



It seems then, that in Java conditions are favourable to 

 volcanic action, water continually filtering through the 

 porous beds to volcanic foci. Hence many of the great 

 eruptions of Java have partaken of the nature of steam 

 explosions, and lava flows are not common. The Papan- 

 dayang eruption blew up the mountain of that name, 

 reducing its height from 9,000 to 5,000 feet, and 'burying 

 forty villages in the debris. The Tomboro and Krakatoa 

 eruptions were on a similar gigantic scale, and of a similar 

 nature. 



V. Sunspot Minima and Earthquakes and Eruptions. — 

 Since my previous paper on the connection between sun- 

 spot minima and earthquakes and volcanic eruptions, I have 

 kept collecting data to test the correctness of the theory 

 which I then put forward. Two letters appeared in the 

 "English Mechanic," on August 15th and August 22nd, 1902 

 respectively, criticising my paper. Their author, Mr. T. B. 

 Espin, examined a number of earthquake records as well as 

 records of volcanic eruptions, and reduced them by the 

 formula 



T = D x — 

 m 



where D = actual time difference between the eruption 



and minimum ahead. 



m = the interval between the two minima between which 

 the eruption took place. 



1 " Borneo" by Posewitz (translation by Frederick H. Hatch, Ph.D., f.g.s.) 



