photographic method it has been found that the effect of Foucault currents is to augment the frequency of the oscillations per second without influencing the number of oscillations in each discharge. Hysteresis destroys the oscillations and diminishes, more or less, the frequency. -A study of the radiographic power of an X-ray tube: S. Turchini. The radiographic effects, as measured by the action on a photographic plate, are found to follow the same laws as the radioscopic effects, and there is reason to suppose that the radiotherapeutic effects will follow similar laws as regards the relation between efficiency and the length of the equivalent spark.-On the conductivity of the gases from flames: Eugène Bloch. The ions contained in the gases given off from a flame, at the end of a time sufficiently long take a mobility of the order of 0.01 mm., and hence should be classed as large ions.-On the ionisation and coefficient of magnetisation of aqueous solutions: Georges Meslin.-The properties of pyrrhotine in the magnetic plane: Pierre Weiss. On the causes of varieties of halation in photographic plates: A. Guébhard. -The triboluminescence of metallic compounds: D. Gernez. The luminous effect observed when certain crystals are broken is not, as has been supposed, essentially a property of organic compounds, and a list of seventy-four inorganic compounds is given in which this effect has been observed. The properties of some anhydrous chlorides of metals of the rare earths: Camille Matignon. Details are given of the crystalline form, colour, density, melting points, heats of solution and formation of the chlorides of lanthanum, praseodymium, neodymium, and samarium. -On a reaction of rhodium: Piñerûa Alvarez. Chlorine, acting on an alkaline solution of a rhodium salt, gives a characteristic blue colour, due to the formation of sodium perrhodate. The action of the metal ammoniums on alcohols : a general method for the preparation of the alcoholates: E. Chablay. The alkali ammoniums, acting upon a solution of the anhydrous alcohol in ammonia, give a quantitative yield of the alcoholate.-Propionylcarbinol and its derivatives: André Kling.-Contribution to the study of the derivatives of benzodihydrofurfurane: A. Guyot and J. Catel.--On methæmoglobin: M. Piettre and A. Vila.-Researches on the mode of action of philocatalase: F. Batelli and Mlle. L. Stern. The name philocatalase is given to a ferment which is present in many animal tissues, although without direct action on catalase it possesses the property of protecting the catalase against the destructive action of anticatalase. The present paper deals with the mechanism of this reaction. -Researches on the comparative power of adhesion of different copper solutions employed as a remedy against mildew E. Chuard and F. Porchet.-On a bacterial decay of cabbage: Georges Delacroix.-The classification and nomenclature of arable earths according to their mechanical constitution: H. Lagatu.—The termination of the motor nerves in the striated muscles of man: Odier. On the problem of statical work: Ernest Solvay. -On the overlapping strata in the Piedmont zone: Maurice Lugeon and Emile Argand.-On an extraordinary halo: M. Pernter. R. ROYAL INSTITUTION, at 5.-Electro-magnetic Waves: Prof J. A. Fleming, Kirby-Note Supplementary to a Paper on the Electric Driving of Winding-gears: F. Hird.-Electric Winding engines at the Exhibitics of the North of France, Arras, Pas-de-Calais: Ed. Lozé.-The Education of Mining Engineers in the United States: Prof. Howard Eckfeldt-Ar Outline of Mining Education in New Zealand: Prof. James Park.-Goa^ blasts in Mines in the Giridih Coal-field, Bengal, India: Thomas Adamson. LINNEAN SOCIETY, at 8. CHEMICAL SOCIETY, at 8.-(1) The Constituents of the Seeds of Hyd carpus Wightiana and Hydnocarpus Anthelmintica. Isolation of a Homologue of Chaulmoogric Acid.-(2) The Constituents of the Seeds of Gynocardia Odorata: F. B Power and M. Barrowcliff-The Relation of Ammonium to the Alkali Metals. A Study of Ammonium Magnesium and Ammonium Zinc Sulphates and Selenates: A. E. H. Tutton.-Canphorylazoimide: M. O. Forster and H. E. Fierz.-Influence of Substitetion on the Formation of Diazoamines and Aminoazo-compounds. Part III. Azo-derivatives of the Symmetrically Disubstituted Primary Meta diamines: G. T. Morgan and W. O. Wootton.-Diazo-derivatives of Mono-acylated Aromatic Para-diamines : G. T. Morgan and Miss F. M. G. Micklethwait.-The Significance of Optical Properties as Connoting Structure; Camphorquinone-hydrazones-oximes; a Contribution to the Chemistry of Nitrogen: H. E. Armstrong and W. Robertson.-Solubility as a Measure of the Change undergone by Isodynamic Hydrazones. (1) Camphorquinonephenylhydrazone. (2) Acetaldehydephenylhydrazone: W. Robertson. The Design of Gas-regulators for Thermostats: T. M Lowry. The Constitution of Barbaloin. Part I.: H. A. D. Jowett and C. E. Potter.--Influence of Substitution on the Formation of Diazoamines and Aminoazo-compounds. Part IV. 5-Bromo-as(4)-Dimethyl-2 : 4diamine-toluene: G. T. Morgan and A. Clayton.-The Action of Hypobromous Acid on Piperazine: F. D. Chattaway and W. H. Lewis. The Action of Magnesium Methyl Iodide on Pinene Nitroso-chloride W. A. Tilden and J. A. Stokes. - Racemisation Phenomena during the Hydrolysis of Optically Active Menthyl and Bromyl Esters by Alkali. A. McKenzie, and H. B. Thompson.. FRIDAY, JUNE 2. INSTITUTION OF MINING ENGINEERS (in the Rcoms of the Geological Society), at 10.30 A. M.-The Conveyor-system for filling at the Coal-face, as practised in Great Britain and America: W. C. Blackett and R. G Ware. Underground Fires at the Greta Colliery, New South Wales: J. Jeffries.-The Geology of Chunies Poort, Transvaal : A. R. Sawyer.-Underground Horses at an Indian Colliery: T. Adamso 1.— Description of the Eimbeck Duplex Base-line Bar: W. Eimbeck. SATURDAY, JUNE 3. ROYAL INSTITUTION, at 3.-Exploration in the Philippines: A. H Savage Landor. Fictitious Problems in Mathematics.-A. B. Basset, F.R.S.; Dr. E. J. Routh, F.R.S. On the Spontaneous Action of Radio active Bodies on Gelatin Media. (Illustrated.)-John Butler Burke The Consolidation of the Earth.-Rev. A. Irving The Spirit-level as a Seismoscope. -G. T. Bennett A Feather-like Form of Frost. Warner The Evolution of Engraving in the Stone Age. (Illus trated.) By A. C. H. 73 74 75 76 -6 (Illustrated.)-H. M. By Sir H. H. $3 The New Diplodocus Skeleton. (Illustrated.) Our Astronomical Column: Newly Discovered Nebula The Bruce Telescope Reference Photographs The Royal Society Conversazione Atmospheric Electricity Observed from Balloons. University and Educat on il Intelligence Diary of Societies . . TWENTY-SIX CRADUATED EXERCISES IN GRAPHIC STATICS, some in Two Colours, and with Skeleton Data to practise upon, and including the Application to Roofs, Moving Locomotives, Retaining Walls, Lévy's Steel Arches, Girders (Original Constructions), Masonry Arches, Lévy's Weight Tables, with an Essay on Graphical Statics, in the form of a Running Commentary on the Exercises, each of which has full Instructions printed on its face, the whole forming a Supplement to the Authors' Elementary Applied Mechanics. By T. 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