192 
NATURE 
[Fune 25, 1885 
an objective tube containing a lens and a diaphragm turned towards 
the source of light with two slits lying above each other, a prism 
for decomposing the two bundles of incident rays, and a second 
collimator tube, on the lid of which closing the end appeared 
two spectra showing an interval between them. Before the lens 
of the ocular collimator was placed a twin prism, the two prisms 
of which with their refracting edges of 1° to 2° were cemented 
together. By this twin prism each spectrum was decomposed 
into two spectra, and the dimensions of the twin prism were 
determined in such a manner that on the lid of the collimator 
one spectrum was situated above, the other below, while 
in the middle the second spectrum of the upper slit coincided 
with the second spectrum of the lower slit. In the lid of the 
ocular tube let a small opening be made cutting offa small piece 
of determinate wave-length from the double spectrum; on 
looking through it the field of vision would be seen divided 
by a line (the refracting edges of the twin prism) into two 
halves, both of the same colouring. Before each of the two 
slits of the objective tube through which the light entered was 
placed a Nicol prism in such a position that perpendicularly 
polarised light entered one slit and horizontally polarised light 
the other. The middle compound spectrum consisted, there- 
fore, of a perpendicularly and a horizontally polarised spectrum, 
and in the field of vision the two like-coloured halves were also 
polarised perpendicularly to each other. If now the field of 
vision was viewed, not directly, but through a Nicol prism, then, 
according to the position of this prism would the one half at 
one time, the other half at another time, be withdrawn from 
sight; and if the two entering rays of light or their spectra 
possessed different degrees of intensity, by turning the ocular- 
Nicol the two halves of the field of vision could be made equal, 
and from the rotation the relative degrees of intensity of the 
two bundles of rays could be determined. 
VIENNA 
Imperial Academy of Sciences, April 16.—Studies on the 
fauna of eighteen smaller and larger Austrian freshwater basins, 
by O. E. Imhof.—On the action of potassium permanganate on 
hyposulphite of soda, by M. Glaser.—On orthoclase as a dry 
mineral in basalt, by V. v. Zepharowich.—On jointed milk-sap 
vessels in the fruit of Zactarzus deliciosus, by A. Weiss.—On 
the relation of Weber’s theory of electro-dynamics to Hertz’s 
principles of the unity of electric forces, by E. Aulinger.-—A 
contribution to aknowledge of the fishes of Turonian system of 
Bohemia, by G. Laube.—On the astronomical data found in 
Assyrian inscriptions, by T. Oppert.—On a new method for 
determination of the size of molecules, by F. Exner.—On a new 
trinitrophenol, by T. Zehenter.—Astronomical researches on the 
Egyptian eclipse referred to in the Bible, by E. Mahler. 
April 23.—On spectrographical experiments on normal light 
sources, and on the applicability of the latter for photo-chemical 
measurement of light-sensibility, by T. M. Eder.—-The know- 
ledge of the anatomical structure of our Loranthacez,; by G. 
Marktanner-Turneretscher.— Researches on chelidonic acid, by 
L. Haitinger and A. Lieben. 
May 7.—On the manufacturing and qualitative composition of 
zirkon, by E. Linnemann.—Systematic zoological studies, by 
F. Brauer.—On artificial uric and methylated uric acids, by T. 
Horbaczewsky.—On polaristrobometric methods, especially on 
**polarimétres 4 pénombres,” by F. Lippich.—Contributions to 
a knowledge of the cobalt ammonium compounds, by G. Volt- 
mann.—On the knowledge of the structure of the Libanon and 
Antilibanon, by E. Suess.—On the solution of Keppler’s prob- 
lem, by Th. von Oppolzer.—On the chlorhydrines of buteryl- 
glycerin, by A. Lieben.—On a crocodile skull found in the 
Tertiary deposits of Eggenburg, Lower Austria, by F. Toula 
nd A. Kail. 
May 14.—On the product of oxidation of propylene oxide by 
silver oxide, by E. Linnemann.—Preliminary communication 
on the fluorescence of the dyeing matters of fungi, by A. Weiss. 
—The knowledge of the structure of the muscles of insects, 
by R. von Limbeck.—On the sinus cavernosus of Dura mater, 
by C. von Langer.—On papaverine, by V. Barth and G, Gold- 
schmidt 
May 20.—Prof. Stefan was elected Vice-President of the 
Mathematical Class; Prof. E. Suess, Secretary; Prof. L. 
Boltzmann (Gratz), Prof. V. von Zepharovitsch (Prague), and 
Prof. C. Claus (Vienna) were elected Members ; Prof. Escherich, 
Prof. A. Vogl, and Franz Exner (Vienna), Correspondents ; 
Prof. A. Bayer (Munich), Prof. T. D. Dana (New Haven), 
Foreign Correspondents. 
May 21.—Anniversary Meeting.—The opening address was 
held by the Curator’s substitute, A. von Schmerling. Then the 
reports were read by the General Secretary, Prof. Siegel, and 
by the Secretary of the Mathematical Class, Prof. Stefan. 
Obituary notes were given by the latter on Hochstetter, Fitz- 
inger, F. von Stein, and Siebold. A prize of 1000 florins was 
awarded to R. Maly (Gratz), for his paper, ‘ Researches on the 
Oxidation of Albumens by Potassium Permanganate.” 
STOCKHOLM 
Academy of Sciences, May 18.—For the Zyansactions of the 
Academy were accepted: Researches on the disjunctive electro- 
motive power on the electrodes during the passage of electricity 
through air of greater or lesser density, by Prof. Edlund ; and 
Ueber die Saugethiergattung Galeopithecus : eine morphologische 
Untersuchung, by Prof. W. Peche.—Prof. Edlund exhibited 
and described a specimen of meteorograph of Thorell’s con- 
struction, made by Herr S6rensen for the Emperor of Brazil.— 
Prof. Warming gave an account of the botanical researches 
undertaken by Messrs. L. Y. Neumann and G. A. Tiselius in 
the Swedish provinces of Jemtland and Medelpad ; and (2) con- 
tributions to the knowledge of the structure of the pericarp, by 
Miss Alida Olbers.—Prof. Toréel exhibited and described a 
geological map of Sweden, on the scale 1 : 600,000.—The 
Secretary, Prof. Lindhagen, presented for publication in the 
Transactions the following papers :—The transversal oscillations 
in a thin crystalline lamina with three plans of symmetry and 
elliptical limitation, by E. Sundberg.—Alpha-oxazonaphtalin 
alpha-sulphonacid and some of its salts, by Dr. J. E. Aleén,.— 
On two isomeric beta-monochlor-naphthalin-sulphonacids, by 
Herr K. Arnell.—On mononitro-beta-naphtha-acids, by Dr. A. 
G. Ekstrand.—Some annotations on microscopic researches on 
plants, by Dr. A. Malm.—Contributions to the flora of fungi 
in the southernmost parts of Norway, by Dr. E. Henning.— 
On Sowerby’s whale, by Dr. A. Malm. 
CONTENTS PAGE 
The ‘Chittagong Hill “Pribes” <2 7) a ee 169 
The Meteorology of Bombay 170 
Our Book Shelf :— 
Supplement to ‘‘ Euclid and his Medern Rivals” 171 
Mojsvar’s “* Leitfaden bei ees -zootomischen 
Prapaririibungen” ...... ° he hat ote mITE 
Letters to the Editor :— 
os ee the Coal-Dust in Mines.—W. Gallo- 
Mo oko. 171 
The P Calnas ‘of Arctic and DIG Animals. —Prof. 
R. Meldola ai See aco oy ae 
Clifford and Prof. Tait—R. 173 
Unusual Atmospheric Phenomenon. —Alex. " Hodg- 
kinson. (J//lustrated) . . MEE to LE 
Sky-Glows.—Dr, F. A. Forel ..... eee 173: 
The International Exhibition—Music ‘Loan Collec. 
tion. By Dr. W. H. Stone. PP fo 8 HEL 
The Measurelof Midget 50 on.) - eee 174 
Recent Earthquakes. By William Scarnell Lean ; 
J. Lovell. 175 
The Scottish Marine Station. “By 7 7. Cunning- 
Lyd COO a Sa oo fC: 176 
Composite Portraits of Members of the National 
Academy of Sciences. Raphael Pumpelly. .. 176 
How the North-Norway Fjords were made. By 
Dr. Karl Pettersen . PS ong OG 177 
Variable Stars... 2. 5 = 6 2 es) 9 oe 
IGE Fs aa 5 556 oes 3 & ee ee eO) 
Our Astronomical Column :— 
The Periodical Comets of De Vico and Barnard 183 
The Double-Star 19 (Hev.) Camelopardi ..... 184 
A Daylight Occultation of Aldebaran. . = den SS 
Astronomical Phenomena for the Week "1885, 
June 28to July ac oe =) es one 183 
Geographical Notes 184 
Electrical Definitions, Nomenclature, and Nota- 
tion, By Prof. Andrew Jamieson, C.E. (//lustrated) 184 
The Jubilee of the Statistical Society ..... A estes 
University and Educational Intelligence ..... 188 
ScientificiSenalgi-gw-- iis aie, eh © el po, gate 
Societies and Academies. . *) Sins, fogs nee 189 
