TRANSACTIONS OF SECTION A. 527 



Still greater age of ninety-five. He was Vice-President of the British Association 

 in 1865. 



Of other countries, America has lost Professor J. Willard Gibhs, a mathe- 

 matical physicist whose very learned and original contributions to the knowledge 

 of the world on the thermodynamical properties of bodies, on vectors, the kinetic 

 theory of gases, and other abstruse subjects, have received the highest recognition 

 that the learned societies of this country can bestow. Professor Harkness, the 

 astronomer, and Professor Rood, the skilled experimental physicist of Troy, have 

 also maintained the liigh standard that we now look for in American science. 



Germany has lost Professor Deichmiiller, Professor of Astronomy at Bonn, 

 at an early age. Sweden has lost Professor Bjerknes, whose hydrodynamical 

 experiments showing attraction and repulsion were so much admired when he per- 

 formed them at a meeting of the Physical Society some twenty-five years ago. 

 Switzerland has lost Professor C. Dufour, the astronomer; and Italy has lost 

 Professor Luigi Cremona, a foreign member of this Association, Principal of the 

 Engineering School in Rome, whose contributions to pure geometry and to its 

 applications have made him famous. 



Of the events of the last year, one stands out beyond all others, not only for 

 its intrinsic importance and revolutionary possibilities, but for the excitement that 

 it has raised among the general public. The discovery by Professor and Madame 

 Curie of what seems to be the everlasting production of heat in easily measurable 

 quantity by a minute amount of a radium compound is so amazing that, even now 

 that many of us have had the opportunity of seeing with our own eyes the heated 

 thermometer, we hardly are able to believe what we see. This, which can 

 barely be distinguished from the discovery of perpetual motion, which it is an 

 axiom of science to call impossible, has left every chemist and physicist in a state 

 of bewilderment. Added to this, Sir William Crookes has devised an experiment, 

 characteristic of him, if I may say so, in which a particle of radium keeps a screen 

 bombarded for ever, so it seems, each collision producing a microscopic tiash of 

 light, the dancing and multitude of which forcibly compel the imagination to 

 follow the reasoning faculties, and realise the existence of atomic tumult. Thanks 

 to the industry and genius of J. J. Thomson, Rutherford and Soddy, Sir William 

 and Lady Huggins, Dewar and Ramsay, and others in this country, besides Pro- 

 fessor and Madame Curie and a host of others abroad, this mystery is being 

 attacked, and theories are being invented to account for the marvellous results 

 of observation ; but the theories themselves would a few years ago have seemed 

 more wonderful and incredible than the facts, as we believe them to be, do 

 to-day. An atom of radium can constantly produce an emanation, tliat is some- 

 thing like a gas, which escapes and carries with it wonderful properties ; but 

 the atom, the thing which cannot be divided, remains, and retains its weight. 

 The emanation is truly wonderful. It is self-luminous, it is condensed by 

 extreme cold and vapourises again ; it can be watched as it oozes through stop- 

 cocks or hurries through tubes, but in amount it is so small that it has not yet 

 been weighed. Sir William Ramsay has treated it with a chemical cruelty that 

 would well-nigh have annihilated the most refractory or permanent known 

 element ; but this evanescent emanation comes out of the ordeal undimmed and 

 undiminished. 



Not content with manufacturing so remarkable a substance, the radium atom 

 sends out three kinds of rays, one kind being much the same as Riintgen rays, 

 but wholly difi'erent in ionising power, according to the experiments of Strutt. 

 Each of these consists of particles which are shot out, but they have different 

 penetrative power ; they are differently deflected by magnets and also by electri- 

 city, and the quantity of electricity in relation to the weight is different, and yet 

 the atom, the same atom, remains unchanged and unchangeable. Not only this, 

 but radium or its emanations or its rays must gradually create other bodies 

 different from radium, and thus, so we are told, one at least of those new gases 

 which but yesterday were discovered has its origin. 



Then, again, just as these gases have no chemical properties, so the radium 



