viii PREFACE 



by pure empiricism. Many geologists have long sus- 

 pected that two sets of deforming processes might be 

 sufficient to account for the diversity that distinguishes 

 the features of our planet, and now some promise of 

 discovery in this direction does indeed seem to be dawning. 

 The great meridional zone of folding and dislocation, 

 resulting from its original pear-shaped form, and the 

 equally great equatorial zone, due to its diminishing oblate- 

 ness, may furnish on further investigation a solution of 

 this problem. 



The third article, on the " Lipari Isles," almost needs 

 an apology for its somewhat too lively manner, so oddly 

 in contrast with the gravity of its companions. Some- 

 thing perhaps may be allowed for the influence of the 

 subject ; it was written immediately after returning from a 

 first personal acquaintance with volcanos in activity, and 

 published as a Christmas article in the Daily Express of 

 Dublin, in company with a number of others contributed 

 by my colleagues in Trinity College. It has been 

 extended by an attempt to account for the explosive 

 character of a volcanic eruption on simple mechanical 

 principles. 



The story of "Funafuti," delivered as the Friday 

 evening lecture to the British Association at its meeting 

 in Bristol, and afterwards published in Natural Science, 

 relates to an attempt to bore through a coral reef in the 

 middle of the Pacific Ocean, in the hope of discovering 

 its structure and history, and so to set at rest a long- 

 standing controversy. The attempt failed, but was 

 renewed under other auspices, and brought to a 

 triumphant issue ; the results, which confirm the truth 

 of Darwin's theory, form the subject of the " Sequel," 

 which appears here for the first time. 



The "Formation of Flints" is also new; it gives a 

 connected account of the results of observations and dis- 



