practically untouched, and a rich field is open for mathematical investigation in this portion only of the subject. In all cases, whether a fluid ether is an actual fact or not, the results obtained will be of special interest as types of fluid motion. It is at present a subject in which the mathematicians must lead the attack. I shall have attained my object in choosing this subject for my address, if by it I can induce some of our younger mathematicians to take it up, and work out its details. The following Papers and Report were read : 1. On the Reichsanstalt, Charlottenburg, Berlin. By Sir DOUGLAS GALTON, K.C.B. The original idea of this establishment emanated from von Helmholtz and Werner von Siemens. The site at Charlottenburg, about 11 acres, was given by Dr. Werner von Siemens, and he contributed 250,000 marks (12,0007.) in aid of the building. Thereupon the German Government undertook the construction of the building and its endowment. The design of the buildings and the working arrangements were planned by von Helmholtz, who was appointed its first director. One portion of the establishment is complete and in operation. The buildings for the other portion are still in course of erection. The scientific work of the second portion is meanwhile being partially carried on in the Royal Technical High School, situated at Charlottenburg. As the establishment is thus still far from complete, the cost of the building and equipment, and of the annual expenditure for maintenance, cannot be given. The object of the establishment may be defined to be the development of pure scientific research, and the promotion of new applications of science for industrial purposes.' The establishment consists of two divisions. The first is charged with pure research, and is at the present time engaged in various thermal, optical, and electrical and other physical investigations. The reports on many branches of work which have been done in this establishment are appended to the paper. The second branch is employed in delicate operations of standardising and testing to assist the wants of outside research students, and to facilitate applications of science to industries. As, for instance, comparison with standardsof the dilatation of metals, of electrical resistances, of electric and other forms of libt. of lenses, of pressure gauges, of recording instruments, thermometers, pyrometers, and tuning-forks, experiments on the qualities of glass, examination of oil-testing apparatus, viscosity of glycerine, &c. The plans exhibited give a general idea of the size of the establishment, which stands in its own grounds, of which the space not covered by buildings is laid out in gardens. The principal building is occupied by the first division; it faces the northwest, and stands at some distance back from the road. This building is about 100 feet long and 85 feet deep. It has three floors of laboratories, and a basement which stands on a mass of cement concrete 2 metres thick, so as to protect the apparatus from vibration; but notwithstanding every precaution, the passing of heavy waggons in the road occasions some movement. An electric tramway is talked of. If this be constructed, serious injury will result to the institution. In this building there are thirty separate apartments devoted to laboratories, in addition to the several official rooms required for the director and staff, and there is also in the building a large and excellent library of works on pure and applied science. To the south of this, and parallel to it, is the building for the second division. This building is nearly 200 feet long, and there are two wings, each of which projects to the south to a distance of nearly 95 feet. This building also is three storeys in height. In the second division there are about forty-one or forty-two apartments devoted to laboratories, in addition to a considerable number of rooms required for the director, the clerks, and the staff, and for a small library. Towards the front on the eastern side, but nearer the road, is the director's house. On the western side is a house which affords apartments for two of the assistants, and a meeting room for the Board of Management and subsidiary clerks' offices. Behind the latter building, on the west side, are placed the engine house, and rooms for dynamos and storage batteries, as well as laboratories for operations in which the use of cold air is required. These are in course of construction. These buildings are equally convenient for the supply of power to both divisions. Two important questions for a department of pure research are: first, the management and the arrangements for regulating the subjects of research; secondly, the methods of taking stock of the work done in the establishment. In the Reichsanstalt the President is supreme over the staff. The successor to v. Helmholtz is Dr. Kohlrausch. He takes charge of the first division, viz., that of pure research. The Director, Professor Hagen, under him, takes charge of the second division. Each main division is subdivided into separate departments for each branch of research; these are in charge of permanent professors. Each of these has under him the necessary assistants selected for limited periods, and for previous good work in one or other of the universities or scientific schools of Germany. The general supervision is under a Council, consisting of a President of the Council, who is a Privy Councillor, and twenty-four members, including the President and the Director of the Reichsanstalt; of the other members, about ten are professors, or heads of physical or astronomical observatories connected with the principal universities in Germany. Three are selected from leading firms in Germany, representing mechanical, optical, and electric science, and the remainder are principal scientific officials connected with the Departments of War and Marine, from the Royal Observatory at Potsdam, and from the Royal Commission for Weights and Measures. This Council is summoned to meet when required, but it generally meets in the winter, for such time as may be necessary, for examining the research work done in the first division during the previous year, and for laying down the scheme for research for the ensuing year, as well as for suggesting any requisite improvements in the second division. It will be seen that the safeguard for ensuring good research work on subjects of general interest and importance lies first in the judicious selection of the President, Director, and Professors of the Reichsanstalt, and after them in a careful selection of the members of the Board of Management, because they not only arrange the subjects for research, but they also hold an annual stock-taking of work done in the department. Members of the Board of Management, who are appointed from the various scientific establishments all over Germany, are carefully selected, and are remunerated for their services. In this country, whilst the more enlightened of the County Councils are forming polytechnic institutions intended to approximate to the higher grade polytechnics in Germany, we have no Government Department which approximates to the Reichsanstalt. The Standards Department was attached to the Board of Trade in 1878, with the duty of making standards of length, weight, and capacity, and in 1889 it was further empowered to make such new standards for the measurements of electricity, temperature, and gravities as appeared to be of use for trade. This department possesses, moreover, under the Gas Acts, powers as to a standard of light. The object of this department is to meet the requirements of trade. Neither the Nation nor the Government appear to have realised the enormous saving of time and labour which would result from systematic standards for every branch of scientific research, coupled with arrangements for comparison easily accessible to students. There would seem to be some difficulty in altering the functions of the Standards Department so as to combine research with its present duties, nor is it established in a situation where delicate observations could be carried on. The Incorporated Kew Observatory, which is administered by a Committee under the Royal Society, is situated in an almost ideal locality for observations. It already conducts, on a small scale, some experimental work, and it appears to afford a nucleus which might be gradually extended into an establishment analogous to the Reichsanstalt, provided the Government would countenance its extension on its present site, and aid the scheme with a grant of money. Under these circumstances, I would suggest that the Committee of Section A upon National Laboratories--which appears not to have been re-appointed at Oxford-be now renewed with members added from Section B and Section G, and that it be requested to report:- (a) Upon the functions which an establishment of this nature should fulfil. ment. The Association would then be in a position to approach the Government with a definite proposal, either for the utilisation of the Incorporated Kew Observatory for the purpose, or for some other plan. 2. On the Teaching of Geometrical Drawing in Schools. The teaching of geometrical drawing in schools is in many respects unsatisfactory. It is at present chiefly regulated by the examinations of the Science and Art Department and those for the entrance into the army. At some schools there are also special classes for those boys who intend to become engineers. The requirements for these are at present quite different. It seems desirable, and not at all difficult, to assimilate the teaching by laying down one rational course, so that all pupils at schools can receive the same instruction, at least in the earlier stages. This should be done first of all without any regard to examinations, the only object being the teaching of the 'art' of geometrical drawing. The syllabus for any examination should then be drawn up in conformity with such a course. To bring this about a committee of the British Association seems to be the most appropriate means. It would be the duty of such a committee to lay down the outlines of the course, and therefore it would be premature to say much about it at present. A few points, however, may here be touched upon. First of all it seems necessary to free the subject, at least at the beginning, from all connection with Euclid and his constructions; in fact, geometrical drawing should be begun long before Euclid is tackled. Euclid only knows two drawing instruments, the straight-edge and the pair of compasses for drawing straight lines and circles. To these should be added at once the set-squares and sooner or later the T-square. The drawing of parallels and perpendiculars should be done by their aid; bisection of lines by their aid and by trial. The first object should be to draw accurately. A great many figures can be drawn, first without circles, where the pupil can judge for himself whether his drawing is accurate. Rules for transforming figures by stretching or by shear may follow, leading to equal and to similar figures. Such a course will be the very best introduction to Euclid, and will form a natural connection between the Kindergarten, which is steadily gaining in importance, and the systematic geometry of Euclid. Solutions of problems which require a knowledge of Euclià should be attempted only when good progress has been made in this art of drawing. 3. Interim Report on Cosmic Dust. 4. Report on Underground Temperature.-See Reports, p. 75. 5. Report on the Sizes of the Pages of Periodicals.-See Reports, p. 77. 6. Report on the Comparison and Reduction of Magnetic Observation. See Reports, p. 209. 7. Interim Report on the Comparison of Magnetic Standards. FRIDAY, SEPTEMBER 13. A joint Meeting with Section B. The following Papers were read : 1. The Refraction and Viscosity of Argon and Helium. As compared with dry air, the refraction (μ-1) of argon is 0.961, and that of helium (prepared by Professor Ramsay) is as low as 0.146. Dry air being again taken as the standard, the viscosity of argon is 1.21, and that of helium is 0.96. 2. On Specific Refraction and the Periodic Law, with reference to Argon and other Elements. By Dr. J. H. GLADSTONE, F.R.S. In 1869, 1877, and 1883 the author had shown that the specific refractive energies of the metallic elements are usually in the inverse order of their combining proportions, and that the specific refractive energies of the elements in general are to a certain extent a periodic function of their atomic weights. The present communication refers to some developments of these old observations. (1) Argon. The specific refractive energy of argon gas, as reckoned from Lord Rayleigh's data, is 0.159. Deeley had suggested that this property might throw light upon the question whether the atomic weight is about 20 or double that figure. The following are the specific refractive energies of the elements with atomic weights between 12 and 23, with the insertion of argon. Carbon, 0·417; nitrogen, 0-236; oxygen, 0·194; fluorine, 003 (?); argon, 0·159; sodium, 0.209. Argon appears to be here in place on the rise which follows the great descent from carbon to fluorine. It does not equally well fit the neighbourhood of calcium, 0.250. If the atomic weight be 1994, the molecular refraction will be 315, which is almost the same number as that for oxygen gas, 3 10, or nitrogen gas, 3'30. (2) The fact that the specific refractive energies of the univalent metals are generally inversely as the square roots of their atomic weights is confirmed by further research, the product of the two being about 13. The same observation is now extended to the earthy metals in the second column of Mendeléeff's table, the products in that case being fully 14. The rule does not apply to the halogens in column 7. As to column 8, iron, palladium, platinum, and gold all give products 1895. R R which are far higher. This confirms the belief that gold is not rightly placed in column 1. (3) It is known that the refraction of a salt when dissolved in water is often slightly modified by the proportional amount of the solvent. The author and Mr. Hibbert have recently found that salts of the metallic elements in columns 1 and 2 of Mendeléeff's table show an increased refraction on dilution, those of metals in column 8 a diminished refraction. 3. A Discussion On the Evidence to be Gathered as to the Simple or Compound character of a Gas, from the Constitution of its Spectrum,1 was opened by Professor A. Schuster and Lord Rayleigh, and the following Papers were read : 4. The Constituents of Cleveite Gas. By C. RUNGE and F. PASCHEN. As the spectrum of the gas contains two sets of lines, each consisting of three 'series,' and no other lines, we may, according to the analogy of other spectra, draw the conclusion that it consists of two, and not more than two, elements. The yellow line D, belongs to the heavier of the two elements, which therefore should alone be called helium. We have separated the two elements to a certain extent by a method of diffusion, the lighter constituent streaming more easily through a plug of asbestos. It was shown that the lines in the visible and in the ultra-red part of the spectrum ascribed to the heavier constituent are less intense relatively to the other lines the earlier the stream of the gas is cut off. The same conclusion that the gas consists of two elements may also be drawn, first from the spectrum of the sun's limb, where the stronger lines of the heavier constituent are always present, while the stronger lines of the lighter constituent are only seen once in every four times. On the other hand in the spectrum of Nova Auriga at its first appearance we have the opposite case, the lines of the lighter constituent being far more prominent. On Motions competent to produce Groups of Lines which have been observed in Actual Spectra. By G. JOHNSTONE STONEY, M.A., D.Sc., F.R.S. In most of the spectra that consist of lines very remarkable groups present themselves, in which the lines are seen to be associated into definite series. In such cases, except under special circumstances, we may safely presume that all the lines of a group arise from the motion of a single electron in every molecule of the gas. Very striking examples of such groups are present in the absorption spectrum of oxygen and in the bright line spectrum of carbon. The oxygen of the earth's atmosphere produces the great A group of double lines in the solar spectrum, as well as the very similar great B group, and the a group. It also produces a group more refrangible than D, about which we know less. This group is much fainter than the others, and it is only under exceptional circumstances that it can be seen at all in the solar spectrum. Each of the other three groups can be distinguished into two sub-groups, which from their appearance have been called a head and a train. The general features of these three groups are the same, and Mr. Higgs has made a careful geometrical analysis of one of them, the great B group. From his analysis we may infer that the head and the train are due to motions in the molecules which are distinct, although related to one another. This conclusion receives further support from the circumstance that in the double lines of 'the head' it is the violet component of each pair which is the stronger, while in the train it is the red component of each pair which is the stronger. In a paper in the Scientific Transactions of the Royal Dublin Society' for 1891, p. 563, the present author pointed out that, if we proceed on the probable Proc. Roy. Soc., 1893, p. 100. |