OTAGO INSTITUTE.

Otago Witness, Issue 2203, 21 May 1896, Page 54

OTAGO INSTITUTE.

A meeting of the Otago Institute niu held at the Museatn on the night of the 12th, and was largely attended, the lecture room being filled to overflowing. Mr A. Hamilton (president) occupied the chair. THE CHALLENGER PUBLICATIONS. Df Pabkeb (iion secretary) read the following letter from Dr Murray, in acknowledgment of a congratulatory resolution passed by the. institute: — Edinburgh, March 6.1890. My Daar Sir,—l am in receipt of your letter of January 21 last, forwarding me a copy of the resa* lution adopted at the anuual meeting of the Otago Institute with reference to the completion of the " Challenger" official publications. I accept with very great pleasure the congratu« lations of your learned institute, and I will always regard this recognition of my labours ia connection with the Challenger expedition as a very high honour. The result, however, is, I feel sure, due more to the kindly co-operation of scientific men iv all parts of the world than to my individual efforts. Be so good as to convey mjr [ best thanks to the members of the institute, and | may I add that the intimation coming from you, whose father was one of the Challenger contribui tors, adds to the pleasure which the resolution has given me. —Youis sincerely, John Murray. Professor T. Jeffrey Parker, F. U.S., Hon. Sec. Otago Institute. NEW MEMBERS. The Peesident intimated that at a meeting of the council the following new members had been elected : —Msairs J. Ewing, W, M'Cou«' nochie, A. T. C&vell (of St. Bvthana), R. (J., ! Whetter, Q. Roberta, Miss Marchanfc, M««sra JA. Michael,'B. 01 Aston, O. W. Hay, and A. J. Kiclßfjon-H\infcsr. GENERAL The Pbesident also intimated thai; Professor Shand had been appointed a member of the council iv place of Mr J. M'Leod (ictnoved to Invercargill), and that Mr G. W. Adams had undertaken to give a lecture on " Fire-raising by FrictibD." bontgen's photohraphtc hats. Dr Shand made a communication on " The E'ectrical Discharge and Profeisor Rontgen'a Photographic Rays." He'naid that when the council of the institute asked him to give an expedition of the natnre of the new discovery which had created so greit a sensation he willingly complied, for he happened to have by him some appliances that would enable him to make the explanation intelligent and eren intel> ligible. Ho need not s*y that he meant to treat the subject purely from -the phy«ical standpoint, and not from the point of view oE the practical photographer, for he regretted to say that he h»d very little knowledge of the practical art of photography; am) he was bound to say that the discovery seemed to him to be fully more important from the scientific point of view than from that of any practical applications of which ifc was capable. Dr Shand gave interesting and beautiful demonstrations of electrical discharge through vacuum lubes; exhausted to various ex'en's, and distinguished the different portions of the discharge, indicating the anode (or positive pole), the cathode (or negative ' pole), the Faraday dark space, and the Crookes dark space, and pointing out that ib was with the phenomena in Cruokes's durk space that they really hai to do, for ib was there fchafc the Routgcn rays had their origin. Re showed how fl'ior<s<:eoce can be excited by an electric discharge and how the effect! called phosphoresconce is produced; and ho then described the original discovery of cathode rays which wera ■ believed to con*i*t of electrified molecules shot violently out from the cathode and which poise3«sd extr<*urd>m,ry p-»wers of ore it ing fluorescence and powers of penetrating objects. Dr Shmd thvn went on to ckscriba the natai'6 of the R6u^g«n rays and explained how upou a barium platino-cyanide plate being placed tu-ar a tube having a current turned on it became illuminated with a fluorescent light. Having exhibited a shadow photograph of a frog, taken by Mr Hamilton, but undtfr-^x* posed, in which the fhadow of the bonus was faintly discernible, Dt- Shand observed that quite 18 mouths ago ib was well known to all physicists that raye %xisbud which had the power of creating fluorescence, the powsr o£ photographing through opaque materials, and ' I the power of discharging electrified bodies. What had produced co great a sensation now attracted to attention wh«u discove red then by Leonard. The speaker believed there *are two reasons for that. Ia the drub place, one of the shadow photographs which Professor Rontgen took was of a human baud in which the ahadows of the boues were very perfectly delineated. Rontgen himself gave no pr minonca to this fact; he remarked it, as ib were, incidentally and dismissed ib in half a dez^o. words. They could not accuse Ro ilgea of suns'itioaulisin ia the matter, but, people reali>ed at once the immvnße help thi» new discovery would ba to surgery. Then, in the second place, Rontgen recognised that he bad got to do with a new kind of radiation, aud this Leonard did not recognise, thinking tint his rays wera cathode rays. Itoatgen threw out the suggestion that this kind of radiation con?i*t<>.d of longitudinal vibrations ia the ether, but phy«icis(;a were rather reluctant to accept such a view. Rou'gen Eeern< d to have been forced to the conclusion in favour of longitudinal vibrations by the exclusion of every other possible hypothesis. Ib was quite inconceivable that this radiation could consist of radiant matter, for the? could not conceive of radiant matter going through boards an inch tbick or through brass plates half an inch thick, and the ide* of ultra-violet light and th<\t of transverse vibrations were equally excluded. There seemed to be no other conclusion than that the new kind of radiation must be longitudinal vibrations. Suoh leading physicists as Lord Kelvin, Professor J. J. Thomson, and others looked not unfavourably on this suggestion, and if this should turn out to be the ens* the discovery formed the germ of a new aud distinct branch of physical science, the outcome of which could not be predicted in any way. If it turned out that the radiation consisted of longitudinal vibrations, the probability was that the vibrations were of exceedingly short period, wh'ch would account for their strong fluorescent properties, and it was also probable that the wave lengths of the rays would be large, which would tccount for their penetrating power. If the rays were of minute period and of great wave length, then theic velocity musb bs enormous—greater than that of light. Dr Shand was loudly applauded at the close of his interesting address. The President expreised the thanks of the members to Dr Shand for the information bo bad afforded them. BEFOBT ON FISHEBIES. The report of the Committee on Fisheries was presented and adopted; aud, on the motion of Mr G-. 11. Thomson, seconded by De Don, a committee, consisting of Mr Hamilton, Dr Parker,' Dr Don, Mr Chapnsan, and ,tha mover, was appointed to co-operate with tha council of the Acclimatisation Society and tha local members of both branches of the Legisla* ture in securing the establishment of a marina fl«h hatchery at Purakanui.

A branch of the National AsflWiatioa tot been formed at Edeudtle.