294 Scientific Proceedings, Royal Dublin Society. 
traced to its true source among the several substances which enter 
into the composition of the deep-sea sediments. The further 
consideration of this point is, however, better deferred till more 
knowledge is obtained. 
It is evident, however, that, if derived from the fem these rich 
deposits of radium go far towards supporting views as to the 
importance of radium in geological dynamics such as I have 
already outlined before the British Association at its last meeting, 
1907. We are logically required to consider the thermal effects 
of these wide-spread deposits of uranium when concentrated in 
ancient rocks and terrigenous sediments. It is my view that the 
secret of the unrest attending sedimentary accumulations may be 
found in radioactive energy. Nor is it without significance that 
in the central Pacific, where by slow degrees much of the heat- 
producing substance has accumulated, the floor of the ocean has 
become disturbed by volcanic energy, and has given evidence 
of movements similar to those which have ordained and con- 
trolled the events of geological history. But, again, more detailed 
consideration is best postponed to another occasion. 
