APPENDIX A LV 



he and Sir A^iilliam Eamsay co-operating were able to verify a prediction 

 of Dr. Rutherford's. They saw the spectrum of Iieliiim grow out of the 

 spectrum of the emanation of radium, i.e., an actual transformation of 

 matter took place before their eyes. Dr. Rutherford had based his 

 prediction on the fact that helium is found on the earth only in con- 

 nection with elements that emit the radiations which have been here 

 spoken of. 



Other transformations have been since observed. More surprising, 

 perhaps, because not anticipated, even in speculation, was the discovery, 

 tliree years ago by M- Curie and M. Laborde, of the enormous amount 

 of energy latent in the atom of radium and released by its disintegration ; 

 an amount sufficient to reconcile the divergent views of Physics and 

 Geolog}' on cjuestions connected with the Sun's heat. 



The aocidental death of ]\I. Curie a month ago in Paris must be 

 a cause of regret to lovers of Science, while the severance of the 

 remarkable partnership in heart and mind of those who by their scientilic 

 eminence, whether separately or in co-operation, have became familiar 

 to all as " the two Curies " an.d have been known in ordinary life as 

 M. and Mme. Curie must touch all hearts. 



Comparison of Recent Advances in Physical Science. 



In briefly noting the advance in one department of Physical Science 

 since the foundation of the Society, I will take for a standard of com- 

 parison, Prof. Tait's work published in 18 ÏQ on the then " Recent Ad- 

 vances in Physical Science." 



It had long been established, by means of the balance, that in spite 

 of appearances, as in the ease of a burning candle, it was impossible to 

 destroy matter, just as it was impossible to create it. This principle of 

 indestructibility is often called the " Conservation of IMatter." 



If we define " energy " as the capacity of doing work — such work 

 as engineers delight in — and measure it, the companion principle of the 

 '' Conservation of Energy " asserts that it is impossible to increase or 

 diminish the quantit}- of energy in the Universe. This principle was 

 established about the middle of the last century. 



But while the quantity of energy cannot be increased or diminished, 

 the form iz readily changed as when a water-fall is used to drive street- 

 cars, or to supply electric light or heat. The Transformation of Energy 

 was fully accepted along with its Conservation. To this there was 

 however at the time of Taif s book no companion principle for matter, 

 or as Tait puts it " The laws of energy dilfer from those of matter in 

 *'■' one most important respect, so far at least as we yet know by experi- 



