432 



NATURE 



[March 2, 1893 



ment of i mm. The column oscillates with each change of 

 temperature and each variation of gravitation, but is not affected 

 by changes of pressure, since the tube is kept closed at the top. 

 Under these circumstances, the instrument in question is 

 capable of indicating the change of gravitational force due to 

 the change in the position of the moon by a displacement of 

 0'46 mm. The apparatus is difficult to set up, and will 

 require some improvement before it can give trustworthy results. 

 — Observation on the conditions which appear to have 

 obtained during the formation of meteorites, by M. Daubree. The 

 heterogeneous structure of meteorites, the innumerable iron 

 granules disseminated through the stony matrix, so different 

 from the well-defined and voluminous crystals obtained by the 

 fusion of the constituent minerals in the laboratory, and M. 

 Stanislas Meunier's success in imitating meteorites by means of 

 gaseous reactions, lead to the conclusion that they have not been 

 produced by fusion, but by a sudden precipitation of different 

 gases into the solid state. — On the preparation of uranium at a 

 high temperature. Rapid preparation of chromium and man- 

 ganese at a high temperature, by M. Henri Moissan (see Notes). 

 — On stereochemistry, by M. C. Friedel. — On the benzoates 

 and metanitro-benzoates of diazoamidobenzene and para- 

 diazoamidotoluene, by MM. A. Haller and A. Guyot. — High 

 atmospheric pressures observed at Irkutsk from January 12 to 

 16, 1893, by M. Alexis de Tilio. During four days the baro- 

 meter remained above 800mm., and on January 14 the highest 

 value known up to the present, 807*5 mm., was reached, the 

 temperature being -aJo'Z C — M.Callandreau was elected Mem- 

 ber in the place of the late Admiral Mouchez ; and M. Kekule 

 Correspondent in the place of the late M. Stas. — Summary of 

 solar observations made at the royal observatory of the Roman 

 College during the last quarter of 1892, by M. P. Tacchini. — 

 On the terms of the second order resulting from the combination 

 of aberration and refraction, by M. Folic. — On the essential 

 singularities of differential equations of a higher order, 

 by M. Paul Painleve. ^Remarks on the preceding com- 

 munication, by M. E. Picard. — On uniform integrals of 

 linear equations, by M. Helge von Koch. — Generali- 

 sation of Lagrange's series, by M. E. Amigues. — On the pait 

 played by the steam jacket in multiple expansion engines, by 

 M. A. Witz. — A direct-reading stereo-coUimator, by M. de 

 Place. — Hysteresis and dielectric viscosity of mica for rapid 

 oscillations, by M. P. Janet. A comparison of differences of 

 potential and resulting charges during rapid oscillations, 

 determined by means of the apparatus described last year, 

 reveals a lagging of the charge behind the potential, both in- 

 creasing and decreasing, and a curve plotted with the values 

 obtained for a mica condenser suggests some analogy with 

 Ewing's curves of magnetic hysteresis. — Optical field, absolute, 

 and relative field of view of the human eye, by M. C. J. A. 

 Leroy. — On the achromatism of semicircular interference 

 fringes, by M. G. Meslin. — A new system of atomic weights, 

 partly founded upon the direct determination of mole- 

 cular weights, by M. A. Leduc. — Decomposition of the 

 alkaline aluminates by carbonic acid, by M. A. Ditte, — 

 On mixtures of ether and water, by M. L. Marchis. — On the 

 heat of formation of arragonite, by M. H. Le Chatelier. — 

 On the crystalline forms of chromium and iridium, by M. W. 

 Prinz. — Ammoniacal fermentation of earth, by MM. A. Muntz 

 and H. Condon. — On the composition of the salts employed as 

 condiment by the people about the Oubangui, by MM. J. 

 Dybowski and Demoussy. — Oxyhsematine, reduced hsematine, 

 and hsemochromogen, by MM. H. Bertin-Sans and J. 

 Moitessier. — On the histological alterations of the cerebral 

 cortex in certain mental diseases, by M. R. Colella. — On the 

 structure and growth of the calcareous shell of the barnacle 

 {B. iinthinabulum), by M. Gruvel. — On the causes of the 

 green colour of oysters, by M. S. Jourdain. — Geological remarks 

 on the diamond-bearing meteoric irons, by M. Stanislas 

 Meunier. 



Amsterdam. 

 Royal Academy of Sciences, January 28. — Prof, van de 

 Sande Bakhuysen in the chair. — Mr. Kapteyn dealt with the 

 distribution of stars in space. It has been long known that the 

 mean proper motion in the galaxy is smaller than elsewhere. A 

 thorough investigation of the "proper motion of a// the stars of 

 the Draper catalogue observed by Bradley in both co-ordinates 

 (2357 stars) shows, that this fact is due to an excess of insensible 

 or very small proper motion in the milky way. Those exceeding 



o"*o55 show no aggregation towards that zone. As far as the evi- 

 dence goes, it further proves, by means of the angle subtended 

 by the solar motion in space, that stars with equal proper motion 

 in and out of the galaxy have nearly equal distances. These two 

 facts taken together prove that Struve's theory of the arrange- 

 ment of the stars in space must be abandoned. In order to find 

 what arrangement must be substituted Mr. Kapteyn has con- 

 sidered the stars of the first and second spectral type separately, 

 and arrives at the conclusion that the latter are very strongly 

 condensed about a centre not far from our system, approximately 

 in the direction of oh. R.A. and -(-42° of deck, whilst the stars 

 of the first type are more nearly evenly distributed in the proxi- 

 mity of our sun. Notwithstanding this difference in arrange- 

 ment Mr. Kapteyn thinks that probability points to the con- 

 clusion that the two types belong to one and the same system : — 

 (i) Because the centre of condensation of the second type stars 

 coincides very nearly with the apparent centre of the milky way 

 (which seems to consist mainly of first type stars). (2) Because 

 the stars with insensible proper motion of both types are strongly 

 condensedtowards the plane of the milky way. (3) Because groups 

 of stars, which undoubtedly form stellar systems {e.g. Hyades) 

 contain stars of both types.— Mr. van Bemmelen, in pursuing his 

 inquiry on colloidal hydrates, spoke at the meetings of November 

 26, 1892, and of January 28, 1893, on the constitution and 

 composition of the hydrogels of SiOg and of CuO, as these 

 result from his determinations of their tension of vapour 

 (at 15°), changing in a continuous way with their tenure of water. 

 —Mr. Kamerlingh Onnes showed the isodynamics of a new 

 physical laboratory at Groningen, mapped under Prof. Haga's 

 direction with the localvariometer by Mr. Wind, proving the 

 excellent constancy of the magnetic field. A new theory of the 

 localvariometer points to another ratio of distances of the de- 

 flecting magnet-pairs than that given by Kohlrausch as preferable. 

 — Mr. Schoute treated of " the uniform.'representation of a cubic 

 surface on a plane." Indication of the number of points com- 

 mon to two curves on F^ the plane representations of which are 

 given. Application as to the position of the twenty-seven lines 

 with respect to one another. 



CONTENTS. PAGE 



Modern Optics and the Microscope. By Rev. Dr. 



Dallinger, F.R.S 409 



A University Extension Manual 412 



Our Book Shelf:— 



Willoughby: " The Health Officer's Pocket-Book " . 412 

 "Engler's Botanische Jahrbiicher fiir Systematik, 



Pflanzengeschichte und Pflanzengeographie " . . . 413 

 Jones : "' Descriptive Geometry Models for the Use of 



Students in Schools and Colleges " 413 



Letters to the Editor:— 



Lion-Tiger Hybrids.— S. F. Harmer 413 



Travelling of Roots.— W. T. Thiselton-Dyer, 



C.M.G., F.R.S 414 



The Flight of Birds.— Herbert Withington ... 414 

 The Niagara Spray Clouds.— Chas. A. Carus- 



Wilson 414 



British New Guinea.— Prof. Alfred C. Haddon ; 



Henry O. Forbes 4^4 



Some Lake Basins in France.— Prof. T. G. Bonney, 



F.R.S 414 



On Electric Spark Photographs ; or. Photography 

 of Flying Bullets, &c., by the Light of the Electric 



Spark. I. (///M5/ra/^fl'.)— By C. V. Boys, F.R.S. . 415 



Notes 421 



Our Astronomical Column : — 



Comet Brooks (November 19, 1892) 425 



Comet Holmes (1892 III.) 425 



Nova Aurigse . 42S 



Hydrogen Line H;8 in the Spectrum of Nova Aurigae 425 



Coincidence of Solar and Terrestrial Phenomena . . 425 



Astronomical Journal Prizes 425 



Geographical Notes 426 



Mongolia and Central Tibet 426 



Gases in Living Plants. By J. C. Arthur 427 



University and Educational Intelligence 428 



Scientific Serials 428 



Societies and Academies 429 



NO. 1218. VOL. 47] 



