INSIDE OF THE WORLD

Evening Post, Volume LXXXVIII, Issue 58, 5 September 1914, Page 3

INSIDE OF THE WORLD

STRUCStTTiE OF THE ATOM LECTURE BY SIR E. RUTHERFORD There are few men who have achieved such eminence in the world of science as Sir Ernest Rutherford, who began his remarkable career at Nelson College, and is now virtually the pioneer and the foremost investigator of the great subject of radioactivity. Last evening he lectured in the Town Hall before a huge audience, explained with probably unexpected clarity a subject with which the great majority of his hearers had only vaguely concerned themselves, and demonstrated some remarkable experiments. Prior to the lecture, the Mayor (Mr. J. P. Luke) extended, on behalf of the city, a formal welcome to Sir Ernest Rutherford and to the other noted scientists, lately delegates to the (Science Congress in Australia, • who were present — Dr. Davenport, Dr. Ely, and Dr. Franklin (of America), and Dr. Thornton (of Newcastle-on-Tyne). Mr. Luke sketched briefly the progress of the lecturer, who, he said, had gained a scholarship at the Havelock School, Marlborough, under the headmastership of Mr. Reynolds, who was among the audience. With that scholarship the young student had gone to Nelson College, and thence to Canterbury

Dr. Davenport, Dr. Ely, Dr. Franklin, and Dr. Thornton also returned , thanks for the welcome. Sir Ernest Rutherford's lecture was, "he explained, on "The Transformation of Matter and the Structure of the Atom." It turned out to be almost wholly concerned with radio-activity, but entirely with the purely scientific aspect of the subject. It had no reference, instance, to the medical use of radium, or to any of the more pic- [ turesque attributes which have been I made familiar to the public. It began with a general dissertation on the changed conceptions, in recent science,' of the constitution of matter, and on the general acceptance of the theory that the atom is a thing permanent, unchangeable, and indestructible and indivisible. The lecturer proceeded to say that scientists had concluded that the atom was nevertheless a very complete structure. He described the discovery of the "electron" — the extremely minute particles, assumed to be merely unit charges of electricity discharged _ from various bodies in certain conditions. From this point there had arisen the theory that the whole of the atomic structure was electrical, and that all matter was really only a complex arrangement of electricity. Dealing, specifically with radium, Sir Ernest entered into particulars of ite genesis from uranium, and its.degeneration to a stage which suggested that ultimately— though this point mas still under investigation — it became lend. He explained that in two thousand years one-halt of any bulk of radium l>ecomcs

ments which had been undertaken for the purpose of counting the particles thiown off during the changes, and described the wonderful instruments by means of which these particles, far too small to be seen by ithe most powerful microscopes, can be actually counted with considerable accuracy. One of these instruments, the "string-electro-meter," was devised by Professor Laby, of Victoria College, and Sir Ernest Rutherford, with Professor Laby's assistance at the instrument, gave an actual and very striking demonstration of the passage of both "alpha" particles and electrons from a specimen of radio-active material. This was, he said, an exceptional demonstration. It had only been given once before in London, and once in Washington. The tact that the particles could, by scientific methods, be counted, and that their relationship to the material concerned was known, the lecturer said, enabled the number of atoms in a body to be calculated. For instance, one cubic centimetre of the gas helium was found to contain 27,400,000,000,000,000,000 atoms— a number which was really inconceivably large. Having staggered the audience with this total, Sir Ernest entered into a discussion of the structure of the_ atom, a matter which he said was specially interesting him at present. He suggested, .roughly, that his investigations showed that each atom consisted of a nucleus and of a number of accompanying electrons. Accepting that the nucleus consisted of a positive electrical charge of so many units (since electrons were always negatively charged), there must be as many electrons as there 'were units in the nucleus to give a neutral electrical condition to the whole atom. If the atom were magnified till the nucleus were the size of the first, then the outermost electrons might be a mile or two away. The actual arrangement of the electrons, and the form and properties of the whole atom, appeared to be governed by the dimensions of the charge of the nucleus. "We are led to believe," he said, "that the atom is thus in itself a great system, and that the nucleus is exceedingly small compared with the atom. And, further, that the nucleus is again a 'great system, held together by forces of enormous intensity, and probably responsible for gravitation and for the radio-activity of certain bodies. We have been able to penetrate the structure of the atom by means of the study of the high-speed projectiles (,tho alpha particles and electrons), but wo have yet no means of penetrating the nucleus. There is still an enormous amdunt of work to be done before we can understand thoroughly the structure of the atom, and so of the whole of the material world." At the conclusion of the lecture, which, in spite of its difficult nature, was clear and keenly appreciated, a hearty vote of thanks was passed to the lecturer", on the motion of Professor Easterfield.