HEREDITY AND RADIUM AT DUBLIN 189 



Professor Joly suggests a new one, which especially pleased the 

 most veteran of the famous geologists present. " We see," he 

 said, " in every case that only after great thicknesses of sedi- 

 ments have accumulated is the upheaval brought about. This 

 is a feature which must enter as an essential condition into 

 whatever explanation we propose to offer." 



Following up the idea that the sought-for instability is refer- 

 able to radio-thermal actions, he attempted an estimate of the 

 rise of temperature in one of these sedimentary areas, and from 

 its amount and also its irregularity drew the inference that 



We have in these effects an intervention of radium in the 

 dynamics of the earth's crust, which must have influenced the 

 entire history of our globe, and which affords a key to the 

 instability of the crust. For after the events of mountain- 

 building are accomplished, stability is not attained, but in pre- 

 sence of the forces of denudation the whole sequence of events 

 has to commence over again. Every fresh accession of snow to 

 the firn, every passing cloud contributing its small addition 

 to the torrent, assists to spread out once more on the floor of 

 the ocean the heat-producing substance. With this rhythmic 

 succession of events appear bound up those positive or 

 negative movements of the strand which cover and uncover 

 the continents, and have swayed the entire course of evolution 

 of terrestrial life. 



The adhesion of even the' most polemical geologists — and 

 they are still not above the Truthful James attitude to Old Red 

 Sandstone — was expressed with surprising unanimity at a long 

 discussion held on the last day of the Dublin meeting on moun- 

 tain-building. Professor Joly himself said nothing about radium, 

 but several of those who had spent the week-end in thinking over 

 the revolution in their science had found all manner of new uses 

 for it. The most ingenious, perhaps, was a suggestion that since 

 the maximum of sedimentary deposits, and therefore of radium, 

 was likely to be found at the edge of the big southern seas, the 

 resulting heat would necessarily increase instability at that point, 

 and so in the sequel produce such great upheavals as the Rockies. 



Perhaps both Mendelism and radium are in danger of being 

 over-exploited. They appear even in the popular press — which 

 recently has grown quite affectionate towards the British 

 Association — and are hailed as the great mystery-probers of the 

 age. But both in their spheres have added immensely to the 

 zest of physical and biological investigation ; and in spite of the 



