OTAGO INSTITUTE.

Otago Daily Times, Issue 3863, 4 July 1874, Page 3

OTAGO INSTITUTE.

A meeting of the Otago Institute was held on the 11th. ult. Mr J. T. Thomson, President, in the chair. NEW ZEALAND BIRDS. Captain Hutton read a paper, entitled "Preliminary-Remarks on some New Zealand Birds,*' by Otto Finsch, Ph. D., of Hon. Member of the Hew Zealand Institute, &c. Captain iiutton having read 3Dr Finsch's paper, said he would draw particular attention to its very great importance. 'He considered it one of the most important contributions to New Zealand ornithology since the voyage of the Erebus and Terror. Captain Hutton mentioned a few cases of birds which he considered were aiot placed in their proper families ; but this paper of Dr Finsch was the first which gave a critical view of birds as regarded their specific character, and which, if it did not quite settle, very nearly settled, the position »£ a great many of them. In the smaller ijirda he had made a great number of alterations, and he (Captain Hutton) thought there would be little doubt they would all turn out correct; and that ■svas certainly doing more than any description of new species. This paper was merely the forerunner of a work by Dr JEinsch, to appear in a year or so, and which ■srould contain a full account of New Zealand birds. The cost of this book would be about ten shillings. It would not be illustrated, but would contain full descriptions. The points now to be settled about our birds ■were;very few to what they were afewyears Sgo. '' .. : COMETS. The following was read by Mr Skey:—■' Ifotes on the reported collision of Bella's Comet with the Earth's atmosphere. With reference to a paper read before this Institute on 12th March, 1872/ on the Zodiacal light, in which a theory is advanced tending to show that the periodic November meteors form part of that illuminated medium, thus forming a probable clueasto the real direction ©f solar motion in space, it will, I think, be interesting to review the published results which followed the actual collision of Beila's comet with the earth's atmosphere on the 27th of November following, and which confirms in a remarkable manner the hypothesis ,«et forth in that paper of the action which would result from the collision of meteoric vapours with the earth's atmosphere, for it is now generally conceded that to Beila's comet is due the ; magnificent display of shooting stars which, on the night of November 27th, 1872, streamed into our terrestrial atmo-. sphere. This collision may, I think, be fairly considered to be one of the most remarkable astronomical occurrences of modern times, and appears to invalidate the generally-re-ceived opinion as to the solidity of the matter of meteors, Jmd consequently induces us to question the^correctness of what is known as the "Meteoric Theory of the Sun," which assumes the sun's light and heat as being sustainedby its surface being bombarded by myriads of^tid meteors, and the Zodiacal Kght has beee,eonjectured as being an illuminated shower, or rather tornado, of stones which are to furnish their equivalent of heat ami light by the sudden check to their motion when they fell into it. Now, comets are known to be bodies of almost inconceivable tenuity, as proved by the immense perturbations they undergo by the attractiens of the planets, without being able to induce any appreciable effect themselves on the orbits of the planets, or even of their satellites. Another proof of their tenuity is the fact of their not being well seen in teleseopea of high magnifying power, and it is highly probable that a comet, when vary close to the earth, cannot' be seen at all by its ordinary illumination, for its light would be so much, diffused, and would' subtend so large an angle that its illumination would fail to be detected, "•-,,„ • immediately after the meteoric display 'alluded to, it occurred to Clinkerfuesto suggest to the Madras astronomer a search o£,| the heavens nea^Tbeta Centauri, or in direction diametrically opposite to the radiant point of the meteors (Gamma Anclromedae) ior the missing comet, and a cometic-looking object was actually noted by him, but not sufficiently near to that point to render: it demonstrable that the object he saw was the truant comet or any part thereof. . When, 3iowever, we consider the enormous perturbation the comet must have undergone by its proximity to the earth, probably that difficulty might vanish. It has been calculated that the meteor stream of the 27th November, Tivas neaily twelve weeks behind the head «>f the comet. Now we can scarcely suppose that any detached collection of solids should ,ha dragged aftor a comet ; such would surely be contrary to all analogy. The conclusion presents itself that if a comet is so drawn ont, either by perturbations of the planets, or by the resisting medium, the parts so firawn out would be of greater tenuity than the comet itself. "We may therefore fairly infer that matter in a non-solid or vaporous form, when coming into collision with, the earth's atmosphere at orbital velociiies, is competent to produce all the phenomena known as shooting stars and meteors. At a future meeting I shall he prepared to give another paper embodying a series of actual observations "On the direction:—the are subtended—and times of visiIrility of the Zodiacal Li<;ht," made since 3872, tending to confirm the theory that this medium ha_s points of greatest elongation in a line coinciding with that of the sun's motion in space. Mr M'Kerrow considered that the theory .advanced by Mr Skey was very feasible; in

proof of which he mentioned that he had seen the bright star Arcturus while it was eclipsed for an hour or two by the nucleus of the comet of 1858. He saw the star shining through the nucleus, and the lustre of the star was not in the least impaired. That would go to show that if comets were not composed of gaseous matter they were composed of matter very highly attenuated. He had noticed Mr Skey said one proof of this extreme tenuity was the great effect of planetary bodies upon them, and the converse, that they had no influence on planetary bodies. He was not sufficient of a chemist to know how gases would comport themselves in great variety of temperature, bub he fancied there would be a change in their volume when near the sun as compared with what it would be when they were far into space. Mr Skey said it was generally undei-stood comets extended very much when they got near the sun. Dr Cotjghtrey asked, in regard to the spectroscope being applied to comets, whether it had been applied to Beila's comet, and if so, what lines were found ? Mr Skey replied that spectroscopic examination showed they were pretty similar in their composition. Carbon had been discovered, or carbon in connection with hydrogen. He did not know if the spectroscope had been applied to Biela's comet. Captain Hdtxon mentioned that a writer in the London Times, quoted by Mr Skey, seemed to connect them with meteors, and he (Captain Hutton) could not understand how great solid pieces of stone were produced from gas. Mr Skey said violent compression of the comet with the atmosphere might produce them. However, he allowed meteoric stones to be accounted for otherwise. His idea was that in the- meteoric displays mentioned the meteors were not solid, but gaseous. The Chairman had seen the very great comet which appeared in 1843. It stretched over about half an arc of the heavens, and he took daily observations of it with his theodolite. The part visible nearest the sun consisted.of a nucleus extremely attenuated, and behind that a tail which always kept in a direct line from the sun. Mr Thomson then explained his theory of what a comet was, at some length, with the use of diagrams. He considered that the matter of which the comet was composed was in the form of an ellipse, and that all the comet was not visible. The nucleus was luminous, and the sunlight on it produced the tail, which, in his opinion, was mert ly a refraction. A proof that it was a refraction was that, while the comet described its orbit round the sun, the tail always kept in a direct line from the sun. The matter of wl ich the tail was composed did not change its position to keep in a Hue from the sun ; the refraction from the nucleus made visible, as the corret changed its position towards the sun in travelling round, parts which were n< t seen before. The fact of the tail shortening as the comet approached the sun showed that the form of the comet was an ellipse. Mr M'Kerrow said that the tail of a comet moving iv order, as the comet travelled, to keep in a rigid line from the sun, meant a speed which even in astronomy was something enormous; that any matter, however attenuated, could travel at such a speed puzzled him, but there was no difficulty if the chairman's theory were accepted. Mr Thomson then made a remark to show that it was the line of refraction and not the cometary matter that changed its position. Mr Skey said that did away with the difficulty of matter sweeping about ten millions of miles in a few hours, as the ouier end of the comet's tail, were it the matter and not the line of refraction that changed, would have to do. The Chairman accounted for alterations in the appearances of the tails by alterations in the form of the nucleas, the latter change affecting the shape of the refraction. Mr P. Thomson asked if the spectroscope had been applied to the zodiacal light? Mr Skey said it had, but the lesult had been doubted, and no opinion could be formed till more satisfactory examinations had been made. The operations of the spectroscope with regard to the zodiacal light, comets, and meteors, was a subject now exciting great interest. THE FIELD NATURALIST CLUB. Mr P. Thomson exhibited ferns collected during the past season at the excursions of the Field Naturalist Club. A NEW FEATURE. The Chairman mentioned Capt. Hutton had stated that at each meeting he would exhibit objects of interest presented to the Museum. This evening there was paper made in New South Wales from maize, and also a specimen of paper pulp from the red tussock grass of New Zealand, presented by Mr E. M'Glashan. He was not sure, but believed the New Zealand material produced was that from which the company now being floated intended to manufacture paper at the Mataura. There was also the sea snake presented by Mr Small. . The meeting having examined the specimens, broke up.