RADIUM RESEARCHES.

Dominion, Volume 4, Issue 1149, 9 June 1911, Page 6

RADIUM RESEARCHES.

WORK OF LOCAL SCIENTISTS.

A paper by Professor T. H. Laby, of Victoria College, and Mr. P. Burbidge, B.Sc., Senior University Scholar, on the gamma rays from radium was read at tho meeting of tho Wellington Philosophical Society on Wednesday night.

It was explained that radium emits three types of rays, known as the aljiha, beta, and gamma rays. The investigations of Professor Rutherford havo shown that the alpha rays are helium atoms, projected with a very high but varying velocity, about one-twentieth of that of light, or nine thousand miles per second. The beta rays were found almost simultaneously by investigators in France, Germany, and Austria to be negatively electrified particles. It is now knowii that these electrons—possibly disembodied electrical charges—are projected with speeds up to that of light. Their smallness and high velocity S' Te them a higher penetrating power than the alpha rays.

Tho gamma rays (the subject of the author's researches) are the most penetrating rays emitted by radium, and these may bo detected after passing through a foot of iron. There arc two theories as to the nature of the gamma rays'. On the theory of Sir J. ,T. Thomson, "the ray is a pulse in a Faraday tube of force. On the theory of Professor Bragg, it is an electrically neutral particlc projected with a'high velocity. On either view as to the nature of tho rays, they are unlike ordinary light, but have a discontinuous wave front. Light is a disturbance in the ether, which travels out like an expanding soap bubble, while gamma rays may for the purpose of illustration be compared to -the bullets of a bursting shrapnel shell, if either Thomson's or Bragg's theory bo true. But no experiments havo been made to show that this view of gamma, rays is actually and experimentally true. The experiments of the authors are' for that purpose, and show that the effect of the rays is discontinuous in space. Further experiments will be necessary to complete the proof that the wave front itself is discontinuous.

The Royal Society of London lent the radium used in the experiments, and made a grant towards the expenses of the research,which was begun in the Cavendish Laboratory, Cambridge.