222 SEE— TEMPERATURE, SECULAR COOLING [April 20, 



Major Dutton tried to explain the activity of volcanoes by means 

 of periodic outbursts produced by radium, but the distribution of 

 these vents along the shores of continents, on islands and in the sea, 

 while none at all break out in the interior of continents, shows that 

 there is a dependence on the oceans, and proves that radium cannot 

 be the active cause in producing eruptions. For the experiments of 

 the Hon. R. J. Strutt have proved that radium is widely distributed 

 in the rocks of the earth's crust, such as granite; but he found on 

 the other hand, that some basalts show scarcely a trace of it. This 

 does not speak favorably for the view that radium is the cause of the 

 earth's internal heat and volcanic outbreaks. For if radium were 

 the cause basalts ought to be rich in the element which had caused 

 the expulsion of this rock from volcanoes ; and since all granite con- 

 tains abundant radium, volcanoes ought to break out in the interior 

 of continents, such as Africa, Australia, North and South America, 

 Europe and Asia ; but this is contrary to observation. It is not possi- 

 ble therefore to entertain the view that radium has any sensible con- 

 nection with volcanic activity. 



Of late even the terrestrial origin of radium has seemed doubtful, 

 and in Nature of February i, 1907, Professor J. Jolly, of Dublin, has 

 suggested several considerations indicating that radium may come 

 to us from the sun, in the form of infinitessimal corpuscles, expelled 

 principally by the pressure of the sun's light. So far as we can now 

 see this extra-terrestrial source of radium is by no means improbable. 

 But whether this suggestion be verified by time and experience or 

 not, it seems certain that radium in the earth's crust is essentially 

 dormant ; at least it plays little part in the physics of planets such as 

 the earth, except perhaps in chemical transformations. 



It probably is not without significance that in order to make the 

 theory harmonize with the observed temperature gradient, Strutt at- 

 tributes radium only to the crust, and not to the interior matter of 

 the earth. If radium comes from the sun, it would lodge in the 

 oceans, and be carried down into the sedimentary and other rocks^ 

 as now observed. In the absence of decisive proof we must suspend 

 judgment, but at present one can only say that there is no evidence 

 that radium is an important agency in cosmical processes witnessed 

 upon our globe. For the sake of comparison, however, we give 



