Philosophical Institute of Canterbury.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 42, 1909, Unnumbered Page

Philosophical Institute of Canterbury. 1909. First Meeting : 5th May, 1909. Present: Mr. Edgar R. Waite (President), in the chair, and over sixty others. The President briefly referred to the work done by the Council during the recess. He announced that the banquet to Lieutenant Shackleton organized by the Institute had been a success in every way, and would necessitate no call on the finances of the Institute. He made reference to the carrying-on of observations at the Arthur's Pass Tunnel, to the projected visit to the Chatham Islands, and to the proposed schemes initiated by the Council for examining the Christchurch artesian system, and for carrying out a bathymetrical, geological, biological, and physical survey of the Canterbury lakes. The Secretary read letters from Professor E. Rutherford, F.R.S., and from Dr. Alfred Russell Wallace, acknowledging the congratulations of the Institute on receiving their recent honours. The former stated that, as an old member of the Canterbury Institute and as an honorary member of the New Zealand Institute, he took a keen interest in the welfare of the societies affiliated to it. His first papers were read before the former, and he was in no way ashamed of those papers; in fact, he esteemed them as highly as any he had written. Dr. A. R. Wallace, after acknowledging the congratulations, requested the gift of seeds of plants from the subantarctic islands of New Zealand. The President drew attention to the circulars issued with reference to the Hector Memorial. He asked that all who intended to subscribe to such a worthy object should forward their subscriptions to Dr. Charles Chilton at an early date. A large number of donations of books and papers were laid on the table. Five new members were nominated. The retiring President (Mr. E. G. Hogg) delivered his ex-presidential address on “Recent Advances in Astronomy.” After a brief account of the manner in which the light-changes of a variable star are graphically represented, the lecturer showed the light-curves of the stars Algol and β Lyræ, and described the generally accepted view of the physical constitution of these binary stars. He then entered into a detailed account of the recent work of M. Nordmann, in the stars Algol and λ Tauri, by which that observer had been led to believe that the waves giving rise to red and violet light travelled through space with different velocities. M. Nordmann had passed the light from the above stars through thin screens, coloured red, green, and blue, and traced their light-curves for each of the three kinds of light: he found that for Algol the minimum occurred earlier for the rays of light passing through the red screen than for those passing through the blue screen by about sixteen minutes of time. Assuming that Pritchard's estimate of the parallax of Algol was correct, and that Algol's distance from the earth was about sixty light-years, it follows, according to Nordmann, that the longer light-waves travel through space faster than the short waves by about 150 metres a second. In the case of λ Tauri the minimum for red waves prededed that for blue waves by from forty minutes to one hour, leading to the conclusion that this star is about three times as far from the earth as Algol. After referring to M. Lebedew's suggestion that this apparent dispersion of light might be explained by an asymmetrical disposition of the atmosphere of Algol's satellite, the

lecturer explained that the red and violet rays traversing that atmosphere would suffer different amounts of absorption, for as red and violet rays did not occur simultaneously there would necessarily be a difference in the times of their minima. M. Nordmann's curves in the cases of β Lyræ and δ Cephei were exhibited, showing the variation in the form for the light-curve for red, green, and blue light; and the lecturer expressed the opinion that though M. Nordmann had failed to prove that dispersion of light occurred in stellar space, yet he had opened up a new method of studying, from which results of great importance might be confidently expected. The lecturer then dealt with various points of interest which have recently come up in connection with the planet Saturn. After describing the discovery of the ninth satellite Phæbe by Pickering, he discussed the possible explanations of its retrograde motion, and gave a brief summary of Stratton's recent work on Pickering's theory of planetary inversion—an hypothesis which, starting with the assumption that the planets originally rotated in a retrograde direction, seeks to explain their direct rotation by means of solartidal friction. In the case of Saturn, Phæbe had been evolved from its primary befors solar-tidal friction had succeeded in changing its retrograde direction into direct. The lecturer then discussed the peculiar condensations seen by Barnard and Lowell on the rings of Saturn when they recently passed through their “end on” position as seen from the earth, and gave a sketch of the different explanations of the phenomenon which had been put forward by Barnard, Lowell, and Russell. He then referred to the alleged discovery of an outer crape ring recently announced from the Geneva Observatory, and showed how the existence of such a ring would confirm the views set forth by Clerk Maxwell in 1856 as to the physical constitution of the rings and their ultimate destruction. He then alluded to Baldwin's research-work on the variability of Saturn's light with change of phase, from which it appears that the earlier views of Müller and Seeliger on this point are not confirmed. At the conclusion of the address, on the motion of the Right Rev. Bishop Grimes, seconded by Mr. Hitchings, a hearty vote of thanks was accorded the lecturer.