ADVANCES IN PHYSICAL SCIENCE

Otago Daily Times, Issue 23883, 10 August 1939, Page 4

ADVANCES IN PHYSICAL SCIENCE

DR JACK'S ACCOUNT In an address on Tuesday night to the Otago branch of the Royal Society of New Zealand, Professor Jack, who recently spent eight months abroad, gave an interesting account of many of the recent applications of physical science. The principles and uses of several complicated appliances were clearly illustrated by experiments and demonstrations. Throughout his talk, Dr Jack stressed the close connection between the work done in the laboratory and the widespread application of the principles discovered to industry and everyday life. Among the important applications dealt with, were the measurement of noise by an objective electrical meter which had been widely used in England in the mitigation of unwelcome sound, and the analysis of soundwaves by the cathode ray oscillograph. The use this method for studying rapidly varying phenomena had been greatly extended, and it is used in all television receivers. A beat frequency oscillator which' produced sound waves covering the whole audible range enabled the limits of audible frequency of an observer to be measured, and it was a valuable laboratory instrument for producing electrical oscillations of known frequency up to several millions per second. ~ , , The development of modern, highly efficient lamps using electric discharge through sodium vapour or mercury vanour. arid in some cases fluorescent materials within an outer sheath of the lamp to improve the resultant colour, was illustrated by exhibits. Dr Jack demonstrated the beautiful and striking effects which were possible by the skilled arrangement of pure ultraviolet powders when exposed to ultraviolet radiation, one of the patterns being the New Zealand flag in true colours. Second only to electric valves in the range and importance of their applications were photoelectric cells, which convert light rays into electric currents and so enable automatic devices to be constructed for switching on lamps when daylight fades for counting, opening doors, and measuring illumination. The principles underlying the electron microscope were explained by Dr Jack, who said it made possible high magnification combined with great resolving power. The lecturer concluded by discussing some electrical appliances, including the cyclotron and ionisation counter for electrical particles, which had been used in work on atom splitting and the production of radio-active substances by atomic bombardment. Since radium was rare and expensive, mudi work was being done on these artificial radio-active substance"? some of which possess properties similar to. but even more desirable than, radium After Dr Jack had answered some questions, Professor F. G. Soper thanked him on behalf of those present for his address.