17

C— lα

The maximum southerly horizontal disturbing force is seen to occur in summer at 23 h. 30 m. Greenwich or 11 a.m. New Zealand time during the mean equinoctial month at 12 noon New Zealand time, and in winter at 1.30 p.m. New Zealand time. A subsidiary maximum westertv disturbing force occurs in summer at 13h. 40 m. Greenwich or 1.10 a.m. New Zealand time in the mean equinoctial month, and in winter this occurs at 12 h. Greenwich or 11.30 p.m. New Zealand time. During the equinoctial months the variation of northerly disturbing force between Bh. and Kih. Greenwich (7.30 p.m. and 3.30 a.m. New Zealand time) is seen to be very small. There is evidently a very marked difference between the curve for the night hours, the small but decided loop then occurring in summer becoming in the mean winter month a very marked invagination. The nocturnal variation of the easterly disturbing force, indeed, becomes in winter relatively very large, especially during the late, night hours, and bears a much greater ratio to the variation in the daylight hours than it bears in the mean summer month, while this ratio is of an intermediate value in the equinoctial month. As might be expected, the curve for the mean equinoctial month bears a very general resemblance to the curve, for the mean month of the year, but it is larger, and encloses a greater area, which points to a non-uniform progressive change in the amplitudes of the diurnal variations between summer and winter, either in spring or in autumn, or in both, and this may perhaps turn out to be accompanied by and connected with a similar want of uniformity in the rate of change of the absolute values of the magnetic elements during the year. The variations occurring in the early morning hours are characterized in summer by being largely in the northern component, and in winter in the easterly component. During the equinoctial month, the curve is seen to be very approximately symmetrical, about an E.-W. axis, between the daylight hours of 12.30 p.m. to 5 p.m. New Zealand time (1 h. to sh. 30 m. Greenwich), and also between the hours of 20 to 23J Greenwich or 7.30 to 11 a.m. New Zealand time. The effect of the irregular variation occurring outside these intervals is, however, to render the two axes of symmetry non-coincident although parallel, the morning axis of symmetry being to the northward of the afternoon axis, which possibly indicates that non-cyclic which these curves : are affected may-be looked for as occurring outside the above intervals. The mean values of the magnetic elements for the three years considered are as under : —

Through the courtesy of the Royal Society, a copy of the volume embodying the magnetic o'bserva--tions made in connection with the British National Antarctic Expedition of 1902-4 has been received. In it a very considerable importance is given to the share this Observatory took in the conceited programme of observations, and due appreciation is expressed of the action of the Governme.nl in affording the use of the Observatory to the scientific members of the expedition for their work vvhilejn Christchurch. Thanks are due to Dr. Chree, F.R.S., for his kindness in superintending the publication of the results, and for his thorough discussion of them. It is understood that for his forthcoming expedition Captain Scott is also arranging a programme for magnetic work, besides the other scientific work to be undertaken. The expedition will sail from Lyttelton in the " Terra Nova," and all facilities will be afforded as previously by this Observatoiv for their preliminary magnetic work. An account of the magnetic work undertaken in the Sub-Antarctic Islands during flic scientific expedition of 1907 to those islands is published in " The Sub-Antarctic Islands of New Zealand," recently published hv the Canterbury Philosophical Institute, towards the expense of which publication a very considerable grant was made by the Government. Further progress has been made with the discussion of the Magnetic. Survey. It was hoped to obtain a series of magnetic observations at the Kermadec Islands this summer, but it proved impossible to get there since the g.s.s. " Einemoa " did not this year visit those islands, and there was no accommodation for passengers on the Government training ship " Amokura," which made the annual inspection in her stead. A future opportunity will be taken in order to get these observations. It is expected that the discussion of the field observations will be complete, and the survey ready for publication, by the, middle of 191 I. The usual regular meteorological observations were made throughout the year. In conclusion, I have to thank the various private individuals, observatories, and other instil ulions that have kindly forwarded their publications to this Observatory during the past year. I would also express my indebtedness to my assistant, Mr. B. Y. Pemberton, for his invaluable assistance during t he year. -'■■ - Henry F. Skey, B.Sc., Officer in charge of Observatory. 3—C. la.

Declination K. Horizontal Magnetic Vertical-Force. '■) '•- Inclination S.'' Inclination 6 S.: 1902 1903'..' 1904 .. 16° 15-1' 0-22694 16° 18-3' 0-22669 16° 21-8' 0-22644 0-55277 n-7,5286 0-55307 67° 40-8' 67° 42-3' 67 p 44'!' Changes per Annum. 1902-3 1903 I ' ' I + 3-2' — 0-00025 + 3-5' • 0-00025 + 0-00009 + 0-00021 + 1-5' + J-8' eans + 3-35' 0-00025 + o-oooir. + 1-65'