March 12, 1903] 



NA TURE 



453 



(2) the particles which penetrate obstacles with singularly 

 penetrating power ; and (3) the ordinary X-rays. X-rays are 

 waves in the ether, not light, something of that nature ; 

 the penetrating rays are electrons which are shot off. But 

 the most interesting are the first rays, those which are 

 easily stopped ; for these turn out to be atoms of matter 

 shot off with a speed comparable to that of light. It is 

 the first time that matter has ever been known to have such 

 a speed as that. Rutherford, now of Montreal, has measured 

 for the first time the speed of these readily stopped absorb- 

 able particles, and also their mass. He shows that they are 

 atoms of matter, and that they are moving with one-tenth 

 of the velocity of light. 



All hot bodies and all negatively charged bodies are now 

 believed to be giving off these particles ; radio-activity is be- 

 coming quite a common feature. Recently fallen rain drops 

 are radio-active, leaves of plants and most things in sun- 

 shine are radio-active ; the difficulty will be to find something 

 which is not radio-active in some degree, and the commonest 

 kind of radio-activity appears to be the detachment of an 

 electron. Loose charges seem to fly off, apparently by 

 centrifugal force or the jostling of the atoms. 



The size of electrons is known, on the hypothesis that 

 the atom of matter is composed of them, i.e. on the hypo- 

 thesis that the inertia of matter is electrical, or that it is 

 electrically composed of the inertia of these charges. Evi- 

 dence of this is accumulating, and there is reason to believe, 

 not only on philosophical grounds, but in accordance with 

 direct physical experiment, that electric inertia is the only 

 inertia that exists. The size of an electron can then easily 

 be determined. Regard the radius as unknown, the charge 

 as known, the mass as known ; then the size is at once 

 calculable. The size of these electrons is about one hundred 

 thousandth part of the diameter of an atom, otherwise 

 they would not have sufficient inertia. They are the 

 smallest bodies known. There was a time when the atom 

 felt small ; it is not big, it is true, but it is getting to feel 

 quite a large thing beside the electron. To illustrate the 

 difference between an atom and an electron, imagine an 

 electron to be the size of a full-stop as here printed, 

 and an atom a church 160 feet long, 80 feet broad and 40 

 feet high — in an atom of hydrogen there are nearly 1000 

 electrons — imagine those thousand full-stops thrown into 

 that church, and some idea will be obtained of the relative 

 sizes of the electron and the atom. The electrons occupy the 

 atom very effectively ; they are energetic and pushful, though 

 not big. They occupy the atom in the sense that soldiers 

 occupy a country, that is, they will not let anybody else in. 

 The electrons, by the force they exert, will not let anything 

 else in, they make the atom impenetrable ; they also give 

 the atom its other properties and enable it to act chemically. 

 That chemical affinity is electrical force has been known for 

 a long time ; it was suspected by Sir Humphrey Davy. I 

 believe if the atom has no extra or odd electron it has no 

 chemical force ; the atom may have molecular force, which 

 is cohesion, and this point might be explained at greater 

 length ; for in my ideas cohesion is turning out to be elec- 

 trical too, though not in the sense of attraction between 

 ordinary positive and negative electricity. 



The relation of the electron to the atom is a matter of the 

 most intense interest. But it is not to be supposed that the 

 electron is stationary in the atom. The electrons are re- 

 volving round one another at tremendous speed, so that the 

 atom is a region of intense activity. The electrons are not 

 in the least crowded, although there are a thousand in the 

 hydrogen atom, twenty or thirty thousand in the sodium 

 atom and one hundred thousand in the mercury atom ; for 

 consider how far apart are they in proportion to their size. 

 Just as far apart as planets in the solar system are in pro- 

 portion to their size. The distance of the earth from the 

 sun is to the size of the earth very much as the distance of 

 electrons from each other is to their size in a mercury or 

 platinum atom. The fact is, we come to an atomic astro- 

 nomy, and the atom is becoming like a solar system, or like 

 nebulae or Saturn's rings or something of that kind, com- 

 posed of a number of small particles in a violent state of 

 revolving motion and occupying very little of the whole 

 space with their actual substance. They are so small that 

 collisions are infrequent ; so it is in the solar system and 

 heavens generally, collisions do occur, but seldom, because 



of the excessively small sizes compared with the distances 

 at which they are spaced out. 



Taking any family belonging to a sun, i.e. a solar system, 

 it forms something like the same kind of collection as the 

 electrons form in an atom. So when we get in an atom a 

 sort of solar system we begin to question whether there is 

 anything in absolute size at all. It is a question I cannot 

 answer. It has been suggested that solar systems may be 

 atoms of a still larger universe. These are questions that 

 are too hard. But there appears to be no end to the infinity 

 of the universe, and all that we can say is that the prob- 

 ability is that it is infinite in an infinite number of ways. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — The subject for the Adams prize essay of 

 1905 is " Wave Motion of Finite Amplitude and Unchanging 

 Type, in Deep Water." The prize is open to the competition 

 of all who have at any time graduated in the University. 

 The value of the prize is about 225!. Further particulars 

 are given in the University Reporter for March 10. 



The new Lucasian professor will next term lecture on 

 " The Theory of Gases and the Molecular Statistics of 

 Energy." 



Dr. Anningson and Prof. Woodhead will represent the 

 University at the congress of the Royal Institute of Public 

 Health to.be held in Liverpool next July. 



no. 1 74 1, VOL. 67] 



It is reported through Reuter's Agency that a sum of 

 more than 200,000/. has been given to Barnard College, 

 New York, to be used for the purchase of the land adjoining 

 the buildings. The name of the donor is not given. 



A jubilee of the University of Heidelberg will be held 

 next August in commemoration of the revival of the Uni- 

 versity in 1803 by Charles Frederick of Baden. Though the 

 fetes will be on a more modest scale than those which marked 

 the celebration in 1886, an extensive programme is being 

 arranged for the occasion. 



The London School of Tropica! Medicine announces that 

 the Craggs research prize of 50/. will be awarded in October 

 to a past or present student of the school who, during the 

 current year, has made the most valuable contribution to 

 tropical medicine. Full information may be obtained from 

 the medical tutor at the school, Royal Albert Docks, London. 



The senate of the Madras University has passed a resolu- 

 tion, it is reported in the Pioneer Mail, disapproving of the 

 recommendations of the Indian Universities Commission 

 that the system of examinations by compartments should be 

 abandoned. The Vice-Chancellor of the Bombay University 

 at the recent annual convocation advocated the establish- 

 ment of a science school, and urged the raising of a fund 

 of twenty- lakhs of rupees for the purpose. Part of this 

 money, he said, must come from the public and part ought 

 to be provided from the funds for higher education in the 

 Presidency. He thought the Government might be trusted 

 to provide the remainder. 



The will of Dr. H. E. Schunck, F.R.S., who died on 

 January 13, shows that he bequeathed to Owens College in 

 trust for the foundation of a " Dr. Schunck's Endowment 

 for Promoting Chemical Research," the contents of his 

 laboratory and the apparatus, appliances and instruments, 

 to be administered by the principal and professors of 

 chemistry in Owens College and by two other trustees, 

 to be nominated by the council, and by his son, Mr. C. A. 

 Schunck, if he shall be willing to serve. The endowment 

 is for the purpose, not only of research in chemical science, 

 but also of geological, physiological and other sciences, and 

 reports are to be annually presented to the council of the 

 college. 



In the House of Commons on Monday Mr. Brodrick stated 

 that many of the recommendations of the Military Education 

 Committee are to be accepted. The new Director-General 

 of Military Education and Training is to have an advisory 

 board as suggested by the Committee. This body is to 

 consist of the heads of Woolwich, Sandhurst, the Staff 

 College, and the Ordnance College, of two representatives 



