i68 



NATURE 



{June 15, i < 



tion of these values. The apparatus consisted of a U-shaped 

 tube, having at the lower part a long straight tube, united to it 

 by fusion, while above, either branch terminated in a tube 

 twice bent at a right angle, and closed at the lower end. By 

 means of a Hagen air-pump this tube-system was gradually 

 evacuated to a pressure of 1-12,000,000 mm. mercury, and the 

 long straight tube opened under mercury at the lower end. The 

 mercury rose in both branches of the U-tube to barometric 

 height. One of the lateral ends of the apparatus was now kept 

 constant at o° ; while the other was first cooled to - 42°, and 

 then heated to various temperatures ; each time the position of 

 the mercury in the two branches was observed with a catheto- 

 meter, and the difference of their heights gave the vapour-tension. 

 The values so obtained for the vapour-tension of mercury were 

 less for all temperatures than those given by Kegnault. Thus, 

 e.g. Herr Hagen found the tension at 0° = o'OI5 mm., Regnault 

 002; at 20 , Hagen o'o2i, Kegnault 0-037; at 100°, Hagen 

 061, Regnault 075 ; at 20o\ Hagen 16, Regnault 19-9 mm. 

 Though the values now found have no claim to absolute 

 accuracy (owing to the difficulty of taking readings with the 

 cathetometer, through round glass), these experiments at least 

 make certain that the Regnault values for the vapour-tension of 

 mercury, which have passed into all text-books, are considerably 

 too large. 



Paris 

 Academy of Sciences, June 5. — M. Jamin in the chair. — 

 The following papers were read : — On double salts prepared by 

 fusion, by MM. Berthelot and Ilosvay. — Report on the expedi- 

 tion to Cape Horn, by H. Milne-Edwards. This meteorological 

 minion, to start soon, for a year's sojourn at Cape Horn, will 

 have two medical men, Drs. Hyades and Han, who have under- 

 taken to collect and make observations as the Academy may 

 indicate. A Committee of the Academy has urged the Govern- 

 ment to add a preparer of collections, and nominated M. 

 Sauvinet for this post ; total additional cost 3625 fr. The wish 

 is expressed that specialists in zoology, botany, and geology 

 could have been appointed ; but the resources did not allow of 

 this. — Zoological instructions drawn up for the members of the 

 Cape Horn Mission by M. Alph. Milne-Edwards. Special 

 attention should be given to the large mammalia — seals, sea- 

 elephants, otaries, cachalots, &c, some of which are rapidly 

 disappearing. Various penguins and other sea-birds call for 

 study ; the fishes are imperfectly known, and a good harvest 

 from dredging operations may be looked for. — The true puceron 

 of the vine (Aphis vitis, Scopoli), by M. Lichtenstein. — History 

 of standards of the metre, by M. Wolf. — On the waves pro- 

 duced by the emersion of a solid at the surfac . of a quiet 

 wave, when there is occasion to take account of two hori 

 zontal co-ordinates, by M. Boussinesq. — On the boiling- 

 temperature of selenium, by M. Troost. Employing a method 

 described March 29, 1880, he arrives at the figure 665° C. 

 for pressure near 760 mm. It is shown that glasses of small 

 fusibility, such as Bohemian and certain French glasses, may be 

 kept at that temperature without deformation, and so used for 

 long chemical reactions. — On a calorimeter dependent on cool- 

 ing, by M. Violle. This is for use where the^initial temperature 

 is between ico° and 400" or 500 . It consists of a small, 

 narrow-necked bottle of thin glass, with double envelope, and a 

 vacuum produced in the interval before closure. Through the 

 neck is introduced a thermometer and a stirrer. — Determination 

 of the specific heats of small quantities of substances, by MM. 

 Thonlet and Lagarde. The method is designed for pure mineral 

 species (o'l gr. to o'5 gr. ). Its piinciple is this : If two thermo- 

 electric junctions be put in tubes holding a liquid of known 

 specific heat (e.g. water, or oil of turpentine), one may measure, 

 by the deflection in a galvanometer, the rise of temperature 

 resulting from immersion in one of the tubes of a body raised 

 to a known temperature, and compare it with that in a second 

 experiment made with a typical body (e.g. copper). The 

 method (which is illustrated by a figure) is shown to be exact. — 

 On a new condensation-hygrometer, by M. Crova. A small 

 tube of nickel-plated brass, carefully polished within, is closed 

 at one end with ground glass, and at the other with a lens of 

 long focus, through which one looks along the tube towards a 

 light-source. Through two terminal tubulures, the air to be 

 examined is drawn through the tube, which is cooled by means 

 of sulphide of carbon traversed by an air current in a metallic 

 envelope round the tube. The changes of aspect in the tube at 

 the temperature of saturation, enable one to estimate the 

 dew-point to one tenth of a degree. — Law of freezing of 



aqueous solutions of organic matter.?, by M. Raoult. The 

 molecules of different organic matters, dissolved in the same 

 quantity of water, cause sensibly the same retardation in its 

 freezing-point. — Method for determination of the ohm, by M. 

 Joubert. — Influence of the positive electrode of the battery on 

 its chemical work, by M. Tommasi. — On oxychlorides of zinc, 

 by M. Andre. — Action of sulphide of carbon on silicium, by M. 

 Colson. — Preliminary note on didymium, by M. Cleve. This 

 points to the existence of a new element accompanying didymium. 

 The author proposes to designate it provisionally by the symbol 

 Di/3 ; it is characterised by the strong line / = 4335'5. — On 

 a new monochlorinated camphor, by M. Cazeneuve. — On 

 spontaneous fermentations of animal matters, by M. Bechamp. 

 He reviews past researches, and indicates a number of deduc- 

 tions from them. — MM. Cazeneuve and Daremburg called atten- 

 tion to the fact of proof having been given by them in 1874, that 

 in general all the substances called colloid by Vircbow and his 

 school, strongly decompose oxygenated water. — On the nerve- 

 tissue of the spinal cord, by M. Ranvier. — Experimental attempt 

 at anatomical localisation of symptoms of toxical delirium in the 

 dog, by M. Danillo. — Essence of absinthe was injected into 

 dogs. The integrity of the optic thalami is not necessary for 

 production of toxical delirium. The cortical region throughout 

 is exclusively concerned.- — M. Larroque furnished some data 

 regarding the thunderstorm of May 30. In some regions there 

 was torrential rain, in others hail. — On a new combination of the 

 lenses of the microscope, by M. Zenger. With a great focal 

 distance he obtains a magnification equal to 2000. 

 Vienna 



Imperial Academy of Sciences, May 11. — L. I. Fitzinger 

 in the chair. — H. Hammerl, contributions to the knowledge of 

 the formation of hydrates of salts. — P. Wesselsky and R. Bene- 

 dikt, on some nitro-products from the pyrocatechin series. — F. 

 Exner, determination of the ratio-electrostatic and electro- 

 magnetic absolute unit. — A. Tschinkel, communication on ex- 

 periments relating to the action of electricity on the growth of 

 plants. — F. Heger, continuation of the fifth report of the Pre- 

 historic Commission on two excavations near Chotzen (Boh.) 

 and near Hallein (Salzburg). — G. Bruder, contributions to a 

 knowledge of the Jurassic deposits in Northern Bohemia. — E. 

 Stefan, on the lines of force of a field symmetrical round an axis. 



May 25. — Anniversary Meeting.— E. v. Bruecke was elected 

 vice-president in room of V. Burg. — In the Mathematical class, 

 Theodor v. Oppolzer (Vienna), Julius Wiesner, and Emil Weyr 

 Vienna, were elected Members. — Fr. E. Schultze (Gratz), V. v. 

 Ebner (Gratz), M. Neumayr Vienna), L. v. Pebal (Gratz), H. 

 Durege (Prague) Correspondents, Friedrich Woehler (Goltingen) 

 Honorary Member, L. Pasteur (Paris) G. G. Stokes (Cambridge) 

 and T. Loven (Stockholm) foreign correspondents. — The meeting 

 was opened by the curator of the Academy, Archduke Rainer. 

 The reports for the past year were read by the general secretary, 

 Trof. Siegel and the secretary of the Mathematical Class, Prof. 

 Stefan. — Then Prof. E. Much (Prague) gave an address on the 

 economic nature of physical research. 



CONTENTS Page 



Charles Darwin, IV 145 



Mascart and Joubert's " Electricity and Magnetism " . . . 147 

 Uuk Book Shelf : — 



Homes and Auinger's " Fossil Gasteropods." — J. Gwyn Jeffreys, 



F.R.S My 



Letters to thb Editor : — 



The Winter of 1881-82.— Dr. A. Woeikof 150 



The Mean Temperature of the Atmosphere at the Surface of the 

 Earth as Determined by Observations and by Theory. — O. 



Reichbnbach 150 



Sea-shore Alluvion — The"Chesil." — J.B.Redman 150 



Meteor.— E. J. Stone, F.R.S 151 



Earthquakes in Naples. — H. J. Johnston-Lavis 151 



The " PoLYl'HEMUS " 151 



Double Stars. By Dr. W. Doberck {With Diagrams) .... 153 

 The Marianne North Gallery of Paintings of " Plants and 

 their Homes." Royal Gardens, Kew. By W. Botting 



Hemslev 15s 



An Electric Railway (With Illustrations) 156 



The Weather of the Past Week 158 



Notes 158 



Our Astronomical Column : — 



Maskelyne's Value of the Solar Parallax 161 



Comet 1882a (Wells. March 17) 161 



A Suspected Variable Star 162 



The University Observatory, Oxford 162 



Geographical Notes 162 



A New Thermograph. By G. Morgan ELD*iDG*(IVitk diagrams) 163 



Science in Bohemia 164 



University and Educational Intelligence 165 



Scientific Serials 166 



Societies and Academies 166 



