LONDON. Royal Society, November 19.—Sir William Crookes, president, in the chair.—A. Mallock: Note on the circulation of the atmosphere.—Sir Sidney Burrard: The origin of the IndoGangetic Trough, commonly called the Himalayan Foredeep.—G. W. Walker: Approximately permanent electronic orbits and the origin of spectral series. In this paper an endeavour is made find a basis of explanation of spectrum series in terms of strict electrodynamics. The illustrative system consists of a spherical nucleus radius a, with positive electric charge E and a fixed magnetic moment μ It is constrained to be fixed and may be regarded as corresponding to a comparatively massive atom. A single corpuscle with a negative charge e and mass m is free to move under the influence of the forces exerted on it by the nucleus. When the effect of radiation is neglected circular orbits are shown to be possible. The circumstances, stability, and range of these orbits are examined in detail, both for orbits outside and inside the nucleus. Only the inside orbits appear to have a bearing on the problem hand. It is found that there is a class of circular orbits in each of which the angular momentum of the corpuscle has the same value. This result has already been obtained by Conway, who sought to identify the value with Planck's unit. It is here shown that these orbits occur only if the charge of the nucleus is concentrated mainly at the surface, or the material of the nucleus has a large dielectric ratioS Another class of circular orbits exists. They in the equatorial plane of the nucleus, and have different angular momenta. The formuke, although possessing the same general features, are not so simple as those for the Conway orbits. The effect of radiation is next considered. The motion of the corpuscle gives rise to radiation disturbance inside and outside the nucleus, while the nucleus produces radiation in the manner proved by Lamb. The disturbance can be analysed into terms of electric and magnetic type. In each case a series of values of r/a are found for wjiich the reaction on the corpuscle becomes very small, and so it is argued that the corpuscular orbit for which r/a has one of these values is comparatively stable and gives a spectral line. Following Lamb in supposing that the dielectric ratio is great, we find that from the Conway orbits with magnetic type of disturbance we get the recognised Balmer formula, while with the electric type of disturbance we get a series closely resembling the Rydberg formula. In addition to these series we ought to get Lamb's series from the nucleus, but quite consistently with the theory they may be in the infrared or the ultraviolet. In order to fit the formula of Balmer type with the hydrogen series, and taking e/m=1.7 × 107, μ=1.8 × 10–21, the radius of the nucleus required is about 2 × 10–10 cm.—W. Jevons: Spectroscopic investigations in connection with the active modification of nitrogen. IV.—A band spectrum of boron nitride. (1) The interaction of active nitrogen and boron tn chloride or methyl borate develops a band spectrum extending from λ 6371 to at least λ 2 140, with well defined heads degrading throughout towards the red. (2) The new spectrum consists mainly of two distinct systems, in the less refrangible of which each band consists of four heads forming two close doublets. The more refrangible system has single heads, and thus resembles the silicon nitride spectrum described in a previous paper. (3) The wavelengths of the heads have been measured, and the wavenumbers in each system have been classified and represented by formuhe in the usual manner. (4) Chemical and spectroscopic evidence has established that the origin of the spectrum is boron nitride. Boron, carbon, and silicon compounds are thus alike in developing nitride spectra in the nitrogen afterglow. (5) The boron njtride bands, like those of cyanogen, are produced in the electric arc spectrum where they occur, together with bands of the oxide.—Prof. E. Wilson: An additional note on the production of high permeability in iron. It has been shown that if stalloy in laminated ring form is subjected to a magnetising force due to a direct current whilst it is cooling through the temperature at which it regains its magnetic properties, and is at the same time shielded from the influence of the earth's magnetism, the permeability recovered at atmospheric temperature has a maximum value of more than 10,000 when the magnetic induction was of the order 6000 C.G.S. units. It had been shown previously that high values of the permeability can be obtained without the use of a speciar magnetic shield when iron has impressed upon it a magnetising force, due to an alternating current, during the time that it cools through the temperature at which it regains its magnetic properties. As, however, in the lastmentioned case, an iron tube was used to enclose the specimen and became heated with the specimen, it was thought desirable to discover whether the high value of the permeability can be obtained wifen there is no question of magnetic shielding. In the present experiments the specimen of stalloy in ring form was allowed to cool inside a sealed fireclay crucible, when subjected to a magnetising force of 13 C.G.S. units, and at atmospheric temperature a permeability of more than io,ooo was again obtained. Further experiments have been made with stalloy in the form of straight strips. The specimen which consisted of a number of strips side by side was wound with a magnetising coil and then placed inside an iron tube. On allowing it to cool through the temperature at which magnetic quality is regained, when subjected to a magnetising force due to a direct current, the improvement in maximum permeability, wnen at atmospheric tempera tune, was small, and,iad apparently disappeared when retested at the maker's works.