284 



SCIENTIFIC NEWS. 



[Sept. 14, iS 



mjt Wtltigi) ®&$otfatton< 



FULL 



SECTIONAL MEETINGS. 



REPORT OF THE DISCUSSIONS. 



[From our own Reporters.] 



MATHEMATICAL AND PHYSICAL SECTION. 



(Continued from p. 255.) 



Light and Electricity Department. 



Saturday, Sept. 8th. 



Professor G. F. FitzGep»ald, F.R.S., presiding. 



The first paper was on The Harmonic Series of Lines in the 

 Spectra of the Elements, by Professor Dr. Carl Runge, who 

 said that Messrs. Liveing and Dewar, in their researches 

 on the ultra violet spectra of elements, had drawn attention 

 to the appearance of what they called the harmonic series 

 of lines. Similar to the formula found by Dr. Balmer, of Zurich, in 

 1885, for the wave lengths of thirteen lines of hydrogen spectrum, 

 there existed, as Professor Kayser and he (the speaker) had found, 

 formulas for the groups of lines of other elements, which Professors 

 Liveing and Dewar, as he. had before observed, had named the 

 "harmonic series of lines." This series of lines had been com- 

 pared to the series of overtones emitted by a vibrating elastic body. 

 He took the liberty of laying before the section a photographic 

 map of the visible and ultra-violet part of the spectrum of iron. It 

 was meant to serve as an instrument for determining the wave 

 lengths of the lines of other elements, and was going to be copied 

 in phototype and published by the Academy of Berlin, together with 

 the wave lengths of the lines measured by Professor Kayser and 

 himself. The scale on the map was rather inexact, but it sufficed 

 to identify a line so as to be able to look up the wave lengths in 

 the tables. He thought that even the weakest lines had been deter- 

 mined with an exactness of o'l Angstrom's unit, and that the 

 probable error of the sharp ones was less than C03 Angstrom's 

 units. 



Dr. J. Janssen, a foreign member of the Royal Society, addressed 

 the section in French at considerable length on the Application de 

 V Analyse Speclra'e a la Mccanique Moleculaire. Spectres de 

 VOxygine. He said he had made observations on the absorption 

 spectrum of oxygen. He found there was a series of lines in the 

 spectrum, the two most prominent of them coinciding with Fraun- 

 hofer's A and B. There were also a series of bands, the three most 

 prominent being about 628, 575, 477. He said he had shown that the 

 lines depended on the quantity of oxygen through which the light 

 had passed. 



Sir Wm. Thomson, F.R.S., congratulated Dr. Janssen upon his 

 extremely lucid statement. He thought that the French of the 

 Professor would be better understood by members of the Association 

 than would be the English of most of the inhabitants of this island, 

 or, he might add, the English of the neighbouring continent 

 of North America. So important did he consider Professor Jacssen's 

 paper, that he proposed that it should be printed at the expense of 

 th: As:ociation, and circulated amongst the members. 



Dr. Gladstone seconded the motion, which was agreed to. 



A paper on The Absorption Spectrum of Oxygen, written by 

 Professors Liveing, F.R.S., and Dewar, F.R.S., was read by 

 Mr. R. T. Glazebrook, M.A., F.R.S., one of the secretaries 

 of the section. 



Papers on A Vortex Analogue of Static Electricity, and on A 

 Diffusion Pholometer, were read by Professor W. M. Hicks, F.R.S., 

 and Mr. J. Joly respectively, and votes of thanks were passed to 

 those gentlemen. 



The Report of the Committee on Electrolysis was then read. This 

 we may give in some future issue. 



Department of Mathematics and" General Physics. 

 Professor Everett, M.A., D.C.L , F.R.S., etc., presiding. 

 Papers by Professor R. W. Genese, on Centres of Finite Twist 

 and Stretch, and on Recurring Decimals and Eermot's Theorem, 

 were read, for which the author received the thanks of the meeting. 

 The President then read a paper on The Relation between 

 Orbits, Catenaries, and Curved Rays. Professor A. M. Wor- 

 thington, in dealiDg with The Tcnsional Stress and Strain within 

 a Liquid, described the three methods that have been employed by 

 previous observers to subject a liquid to tension. These are : — 

 (1) The barometer tube method, by which Professor Osborne 

 Reynolds had succeeded in subjecting mercury to a ten- 

 sion of five or six atmospheres due to its own weight. 



(2) The centrifugal method, devised by the same observer, and 



by means of which he had subjected water to a pull of 

 about five atmospheres (72^5 lbs. per square inch) ; while 

 the author had succeeded in reaching with alcohol a ten- 

 sion of 7-9 atmospheres, or 116 lbs. per square inch, and 

 with strong sulphuric acid a tension of 11 '8 atmospheres, 

 or I73'4 lbs. per square inch. 



(3) The method of cooling, discovered by Berthelot, and de- 



scribed by him, " Ann. de Chimie " xxx. (1852) : Sur la 

 dilatation forcee des liquides. 



The author then described the form of apparatus, arrived at after 

 many trials, by which the tension of the liquid and the extension 

 produced by it could be simultaneously measured. 



The experimental proof that tensional stress within a mass of 

 liquid is necessarily accompanied by a corresponding strain, was, in 

 the author's opinion, an important point in the theory of surface ten- 

 sion, since it showed that the diminution of density or extension of 

 the surface liquid, which could be shown to be a necessity of the 

 equilibrium at the surface, was sufficient to account for the surface 

 being a seat of energy. It became, in fact, unnecessary to ascribe 

 to the energy any other form than that in which it existed in stretched 

 matter. 



Professor Hele Shaw, M.Inst.C.E., then gave an address on a 

 New Sphere Planimeler. 



Monday, September ioth. 



Mr. Wm. Esson, M.A , F.R.S., presiding. 



Mr. R. T. Glazebrook, M.A., one of the Secretaries, laid before 

 the section the fourth report of the Committee, consisting of Pro- 

 fessor Balfour Stewart (Secretary), Professor W. Grylls Adams, 

 Mr. W. Lant- Carpenter, Mr. C. H. Carpmael, Mr. W. H. Christie 

 (Astronomer Royal), Professor G. Chrystal, Captain Creak, Pro- 

 fessor G. H. Darwin, Mr. William Ellis, Sir J. H. Lefroy, Professor 

 S. J, Perry, Professor Schu.-te>% Professor Sir W. Thomson, and 

 Mr. G. M. Whipple, appointed for the purpose of considering the 

 Best Means of Comparing and Reducing Magnetic Observations. 



He said since their last report the Committee have to jrecord the 

 death of their Secretary, Professor Balfour Stewart, whose loss will 

 be deeply felt in the scientific world, especially by those who are 

 engaged in researches in terrestrial magnetism and in the work of 

 magnetic observatories. A meeting of the Committee was held on 

 February 2nd, 18S8, at which Professor W. Grylls Adams was 

 requested to act as Secretary to the Committee and to forward to 

 the directors of magnetic observatories copies of the third report of 

 the Committee, calling special attention to the paragraphs relating 

 to the determination of scale co-efficients. 



At the second meeting of the Committee, on July nth, 1888, Mr. 

 W. L. Carpenter handed to the Committee a paper which had been 

 prepared by Professor Balfour Stewart, on a comparison between 

 the wind values and declination disturbances at the Kew Observa- 

 tory. The Committee have thought it right to recommend that this 

 paper and the table accompanying it be printed as an appendix to 

 the report. 



The Committee learn that all the scientific material found among 

 Dr. Stewart's papers is in the possession of Professor A. Schuster. 

 Professor Schuster has continued his reduction of the diurnal varia- 

 tion of terrestrial magnetism, and has nearly completed a paper on 

 the subject, which he proposes to present to the Royal Society. 



A paper has also been communicated to the Committee by Major 

 Dawson, on magnetic observations taken at Fort Rae in 1882-83. 



The Hon. Ralph Abercromey read a paper on Modern Views 

 about Hurricanes, as Compared with the Older Theories. He said 

 the old idea of a hurricane was that of a circular-shaped eddy, 

 round which the wind blew in circles ; the whole system was not 

 supposed to be connected with any surrounding trade-wind or mon- 

 soon, and the idea that a hurricane changes its shape, as well as its 

 depth and intensity, during its progress, was never thought of. 



Modern research showed that a hurricane was really an oval eddy, 

 and that the vortex, or centre of the wind rotation, was not in the 

 geometrical centre of the oval, but usually nearer one edge or other 

 of the depression. The former was a very simple, the latter a very 

 difficult conception ; nevertheless, such were the facts, as the 

 author has proved by an examination of hurricanes on sixty different 

 days. 



The wind blew as a spiral of variable incurvature round the 

 vortex, not round the centre of the oval. The general sense of the 

 rotation was counter-clockwise in the Northern, clockwise in the 

 Southern Hemisphere ; but the amount of incurvature varied in 

 different parts of the oval, for a number of reasons. As a rule, in all 

 hurricanes the incurvature was less in front than in rear of the 

 vortex, 



