THE POLAR LIGHTS

New Zealand Herald, Volume LXIX, Issue 21254, 6 August 1932, Page 7 (Supplement)

THE POLAR LIGHTS

STUDY OF PHENOMENA In a lecture before the British Service Guild recently, Professor S. Chapman, F.R.S., pointed out that modern observations of polar lights or aurora have advanced human knowledge chiefly by establishing the heights and situation with incontrovertible accuracy, by the methods of Slormer and his followers; and by the interpretation of the beautifully coloured auroral light with the aid of the spectroscope and tho great body of modern knowledge concerning atomic and molecular spectra. Much remains to be done before the full fruits of tho study of tho auroral spectrum are garnered, but two main facts are established; a largo part of the spectrum consists of bands due to singly ionised nitrogen molecules, while the famous green line, a standing challenge to spectroscopists for many decades, has been shown by McLennan, to be emitted by neutral atomic oxygen; he, his colleagues, and others have traced the line in detail to its source in a particular transition occurring in the oxygon atom. Through the initiative of another active investigator of the auroral spectrum, Vegard, the Rockefeller Foundation has instituted an auroral observatory, maintained by the Norwegian Government, at Tromso; special attention will be devoted afc this well-equipped and favourably situated observatory to this side of auroral research. A further remarkablo observational discovery concerning the aurora, due to Stromer, is the recognition that the specially high aurora, sometimes seen in the west after sunset, or in tho east before sunrise, are in the part of the atmosphere, beyond the earth's shadow, still traversed by the sun's rays. On tho side of theory, the advances have 4)een of comparatively recent date. Birkeland laid the foundations, by his speculations and experiments, on which Stromer has reared a great mathematical superstructure, developing tho hypo.thesis that the aurora is clue to electrically charged particles from the sun; these are deflected toward the polar regions, thus explaining the geographical incidence of tho lights. Stromer has deduced from this hypothesis the existence of tho two auroral zones, and many other observed features of the aurora. But valuable and successful as the present theory is, it suffers, as Schuster indicated, from a great and deep-lying defect. Of the forces which guide the particles, the theory considers only the electromagnetic, whereas there will also be important electro-static forces, which the theory ignores; the latter arise from tho mutual influence of the particles, which must bo partly positive and partly negative, in nearly equal numbers. A new theory must be built up, faking both sets of forces into account; this promises to be exceptionally difficult, and only the merest beginning has yet been made. BREATH OP VEGETABLES Experiments are being made at Cambridge to keep fruit in its freshly-gathered state all the year round. Hitherto it has been found to deteriorate in the course of preservation, but new processes of freezing hold out hopes of improved re suits. In the research station there are instruments for recording when fruit and vegetables cease to live. Life does not end when an apple is gathered or a cab bage is cut, but only when it ceases to breathe. Not until then does decomposi tion set in, and even them the pips of an apple will often go on living and breathing for a few years. Before thg breath ing of the fruit and vegetables can be recorded they must be placed in glass cases. The instruments draw the breath through the glass. Little difficulty is being found in keeping fruit alive over long periods, but the aim is that it shall be as sweet, as juicy, and as delicious when taken out of 'the freezing chambers as when it is put in them. NEW THEATRE PROGRAMME. A new type of programme for theatre use has been invented which can be read in the dark. It is called the glowgramme, and it is made of black cellophane, on which the printing appears transparent. It the glowgramme is held up between the eyes and the lighted stage or screen it can bo easily read. Another advantage is that cellophane, which is not inflammable does not rustle.