448 



NATURE 



[September io, 1903 



He gave one of the evening lectures of the British 

 Association in 1863, the subject being balloon ascents. 



A. F. Osier, the inventor of the self-recording direction 

 and pressure anemometer and rain gauge, whose active 

 meteorological work was carried out in the first half of the 

 last century, when he contributed papers to the British 

 Association and the Literary and Philosophical Society of 

 Birmingham, has died at the still greater age of ninety- 

 five. He was Vice-President of the British Association in 

 1865. 



Of other countries, America has lost Prof. J. Willard 

 Gibbs, a mathematical 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. Prof. Harkness, the astronomer, and 

 Prof. Rood, the skilled experimental physicist of Troy, have 

 also maintained the high standard that we now look for in 

 American science. 



Germany has lost Prof. Deichmiiller, Professor of 

 Astronomy at Bonn, at an early age. Sweden has lost Prof. 

 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 Prof. C. Dufour, 

 the astronomer ; and Italy has lost Prof. 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 Prof, 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 dis- 

 covery 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 

 flash 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 in- 

 dustry and genius of J. J. Thomson, Rutherford and Soddy, 

 Sir William and Lady Huggins, Dewar and Ramsay, and 

 others in this country, besides Prof, and Madame Curie and 

 a host of others abroad, this mystery is being attacked, and 

 theories are being invented to account for the marvellous re- 

 sults 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, that 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 vaporises again ; it can be watched as it oozes through 

 stopcocks 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 sub- 

 stance, the radium atom sends out three kinds of rays, one 

 kind being much the same as Rontgen rays, but wholly dif- 

 ferent 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 dif- 

 ferently deflected by magnets and also by electricity, 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 



NO. 1767, VOL. 68] 



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 which produces them in some re- 

 spects behaves in a manner contrary to that of all proper 

 chemicals. It does not lose its power of creating heat even 

 at the extreme cold of liquid air, while at the greater degree 

 of cold of liquid hydrogen its activity is found by Prof. Dewar 

 to be actually greater. 



Unlike old-fashioned chemicals which, when they are 

 formed, have all their properties properly developed, radium 

 and its salts take a month before they have acquired their 

 full power (so Dewar tells us), and then, for anything we 

 know to the contrary, proceed to manufacture heat eman- 

 ations, three kinds of rays, electricity, and gases for ever. 

 For ever ; well, perhaps not for ever, but for so long a time 

 that the loss of weight in a year, calculated, I suppose, rather 

 than observed, is next to nothing. Prof. Rutherford believes 

 that thorium or uranium, which act in the same kind of way, 

 but with far less vigour, would last a million years before 

 there was nothing left, or at least before they were worn 

 out ; while the radium, preferring a short life and a merry 

 one, could not expect to exist for more than a few thousand 

 years. 



In this time one gramme of radium would evolve one 

 thousand million heat units, sufficient, if converted into work, 

 to raise five hundred tons a mile high ; whereas a gramme of 

 hydrogen, our best fuel, burned in oxygen, only yields thirty- 

 four thousand heat-units, or one thirty-thousandth part of 

 the output of radium. I believe that this is no exaggeration 

 of what we are told and of what is believed to be experi- 

 mentally proved with regard to radium ; but if the half of 

 it is true the term " the mystery of radium " is inadequate : 

 the miracle of radium is the only expression that can be 

 employed. 



With all this mystery before us, which I must confess my- 

 self wholly unable to follow, I feel sure that members of the 

 Association who are interested in the work of this Section 

 will welcome the discussion, for which oui- secretaries have 

 been able to arrange, and hear from the lips of Prof. Ruther- 

 ford the conclusions to which his researches have at present 

 brought him. No one is more fitted than Prof. Rutherford 

 to open such a discussion, for no one has attacked the theo- 

 retical side with such originality and daring, or with such 

 ingenuity of experiment. 



As an example of the activity of mind and of research to 

 which the activity of radium has given rise, I may mention 

 the fact that the last number of the Proceedings of the Royal 

 Society is wholly concerned with radium, there being four 

 papers, all of the first importance, dealing with entirely dif- 

 ferent phenomena. 

 i It is not my purpose to review these or the subject of 

 radium generally ; I am in no way fitted to do so. But I 

 cannot well let the present opportunity pass of referring to 

 I another mystery of which a conspicuous example is now 

 j leaving us. I refer to the mystery of the comet and its 

 I tails. What is a comet? of what does its tail consist? Gravi- 

 tational astronomy has told us for many years past that com- 

 pared with the planets or their satellites a comet does not 

 weigh anything. It weighs pounds or perhaps hundreds, 

 thousands, or millions of tons ; but in comparison with in- 

 conspicuous satellites it weighs nothing. Yet some of them 

 as they approach the sun from remote regions begin to shoot 

 out streamers which pour away as though repelled by the 

 sun, not being left as a trail behind the comet, as is so ofterr 

 supposed. These streamers, ejected towards the sun, bend 

 round and pour away at speeds which are enormous com- 

 pared with that of the comet itself, thus producing the taiL 

 Now these streams separate very often, and give rise to 

 comets with two or three tails. Let me read one paragraph 

 from " The History of Astronomy," by Miss Gierke : — 



" The amount of tail curvature, he [Olbers] pointed out, 

 depends in each case upon the proportion borne by the 

 velocity of the ascending particles to that of the comet in its 

 orbit ; the swifter the outrush the straighter the approach- 

 ing tail. But the velocity of the ascending particles varies 

 with the energy of their repulsion by the sun, and this again, 

 it may be presumed, by their quality. Thus multiple tails 

 are developed when the same comet throws off, as it ap- 

 proaches perihelion, specifically distinct substances. The 

 long straight ray which proceeded from the comet of 1807, 



