Bre 
NATURE 
[Fuly 30, 1885 
posterior surface, in the beams of light falling under different 
angles. These differences of phase, as the speaker demonstrated 
by showing the course of the single bundles of rays produced on 
the retina of an eye focussed for parallel rays, a system of 
coloured and dark concentric rings, similar to Newton’s rings 
of colour. This system of rings appeared, however, only when 
the plates were exactly parallel, at least to as great a degree of 
precision as that of the rays which enter the pupillary aperture 
by reflection from any point. ‘These rings might therefore be 
utilised as a test of the parallelism of the glasses. Deviations of 
o'2 wave-length caused no disturbance in the rings, but differ- 
ences in the thickness of the glass amounting to 0'5 A certainly 
gave rise to such disturbance. Bringing the glass before the eye, 
which was always accommodated to infinitude, considerably large 
spaces of the glass might be tested in reference to their parallelism. 
Any thinning or any thickening of the glass would be at once 
marked by displacements in the ring-systems and their wander- 
ing from the interior to the outside, or from the outside to the 
interior. The speaker compared his method of observing the 
interference phenomena, and testing the parallelism of the glass 
surfaces with that of Fizeau, and brought out the differences of 
the two, as also the advantages of his method.—Dr. Kayser 
gave a report of two works quite recently published on spectrum 
analysis, which seemed to make an important advance in the 
theory of spectral lines. It had formerly been attempted 
in vain to find harmonic relations, such as those existing 
among the upper tones of a sounding body, among the lines 
shown by thespectrum of a metal vapour, but the attempt to find 
such simple relations was abandoned after the question had 
been discussed by Prof. Schuster. Lately, however, Herr Balmer, 
in calculating the wave-lengths of the hydrogen lines, as 
given by Angstrom, had found a relation between these lines, 
expressed by the formula 2= aus ‘C, when C had the value 
ne — 
of 3645°6 millionths of a millimetre. In place of 7 let there be 
put in turn the numbers 3, 4, 5, 6, then were obtained Ang- 
strém’s undulatory lengths of the four visible hydrogen lines. If the 
calculation were carried still further, and for 7 were placed the 
values 7, 8, &c., on to 16, then were obtained values for hydro- 
gen lines which coincided very well with the wave-lengths 
of the lines which Dr. Huggins had found in the ultra-violet 
spectrum of the white stars, and had recognised as the invisible 
hydrogen lines. The longest among these ultra-violet hydrogen 
lines had been photographed by Prof. Vogel in the spectrum of 
a glowing hydrogen tube. This relation between the hydrogen 
lines had now received an increased significance from an in- 
vestigation by Prof. Cornu, in which he had found a perfectly 
determinate proportionality in the lines of the ultra-violet spec- 
trum of aluminium and of thallium to the ultra-violet hydrogen 
lines. Like the hydrogen lines, the pairs of lines of the two 
metals referred to advanced so much nearer to one another, and 
became so much paler the more one approached the more re- 
frangible end of the spectrum ; and if any line of the aluminium 
or the thallium spectrum was made to coincide with the corre- 
sponding line of the hydrogen, then did all the remaining lines 
coincide, This relation obtained both for’ the first and for the 
second lines of the pairs of lines in the metal spectra. —Prof. von 
Helmholtz drew the attention of the Society to an investigation 
of Dr. Wernicke, which will shortly be published, of great import- 
ance for the theory of the reflection of light. The experiments 
had reference to the reflection of thin plates in which each ray 
divided into two, one being reflected, the other refracted and 
again reflected by the posterior surface, in addition, still further 
secondary refractions and reflections came into account. The 
difference of phase in the reflected rays, on monochromatic light 
being applied, was observed through their interference pheno- 
mena. According to the theoretical development given by Dr. 
Wernicke, without any hypothetical assumption whatsoever, the 
difference of phase depended on the sine of the angle of incidence, 
on the cosine of the angle of refraction, and on three constants. 
By examining a large series of solid bodies—transparent crystals 
as well as metal films—Dr. Wernicke found in the case of 
incidences which were approximate to the angle of polarisation 
that, if the plane of polarisation were parallel to the plane of 
incidence, the three constants became zero. If, on the other 
hand, the plane of polarisation was perpendicular to the plane 
of incidence, the constants had a definite value. This experi- 
mental result was in agreement with Fresnel’s theory of reflec- 
tion. According to Naumann’s theory the constants must become 
zero in the case of perpendicular polarisation planes and have a 
definite value in case of parallel direction. According to 
Ketteler’s theory the constants could never become zero. 
STOCKHOLM 
Academy of Sciences, June 10,—The following papers 
were presented for insertion in the Zyansactions of the Academy : 
Contributions to the physiological anatomy of the alge, by 
Herr N. Wille.—On Japanese cephalopoda, by Herr A. 
Appellof, B.A.—On the determination of the amount of 
electromotive power of the voltaic arc, by Prof. E, Edlund.— 
Contribution to the question of the action of fluidity upon the 
electric conducting power of electrolytes, by Dr. S. Arrhenius. 
— Researches on the electric spark in fluids, by Dr. C. A. Mebius. 
—On the conformation of the hypostoma in some Scandinavian 
Asaphids, by Prof. W. Brégger.—On an Inoceramus from 
Queensland, by Prof. B. Lundgren.—A catalogue of the 
Silurian crustacea of Gothland, I. Trilobites and Merostoma, by 
Prof. G, Lindstrom.—On intermediate orbits, which at a 
given moment with a contact of the third order, join with the real 
orbits, by Prof. Gyldén.—On alcohol in beer, by Prof. Hamberg. 
—On marine vertebrates from the northernmost part of the 
province of Tromsé and West Finmark, by Dr.. C. Aurivillius. 
—On rhodonite from Pajsberg and Langbau, by Hen. G. 
Flink.—On the crystallographic constituents of godolinite, by 
Hen. F. Eichstedt.—Crystallographic researches on the rarer 
metals, by Hen. C. Morton.—On some combinations derived 
from dicyanphenylhydracin, by Dr. J. J. A. Bladén.—On 
melanism and combinations of melam, by Dr. P. Claesson.— 
Some speculations and experiments on filtration in its bearing 
upon the processes of transudation in the animal body, by Drs. R. 
Tigerstedt and C. G, Santesson.—Prof. Smitt reported on the 
International Ornithological Congress in Vienna of last year.— 
Prof. Wittrock exhibited the first fasciculus of the fodder-herbs 
of Sweden, edited by Drs. Jonsson and Whalsted, and gave an 
account of a report on a botanical expedition to Norrland and 
Norway, for the purpose of studying the morphology and 
phylogeny of the Hierarsia, by D. S. Almquist. 
CONTENTS Pacr 
The University of London . PR Oa oak) 
The Evolution of the Phanerogams. By J. Starkie 
Gardner 2 5 3 5 1s se oe See 
Harboursiand Docksy-—- eee 291 
Our Book Shelf :— 
Fol’s ‘* Lehrbuch der vergleichenden Mikroskopischen 
Anatomie:/— Dr. Jein yu ee Oe 
Letters to the Editor :— 
Unconscious Bias in Walking.—Manly Miles . 293 
The Flora of Canada.—Alfred W. Bennett 294. 
The Fauna of the Seashore.—W. R. Hughes 204 
Artificial Earthquakes.—T, C. Lewis ...... 2095 
The Recent Earthquake in Switzerland.—F. A. 
Forel 2. 2 se + * 6 os 3 eer 
The Pitcher Plant... ... . « 5. «> «we eeZos 
The Eclipses of August, 1886 .......... 206 
International Inventions Exhibition. By [Henry 
Dent Gardner POMOC Ooo EIA 
The Nice Floating Dome. (J/ustrated)...... 297 
A New Endowment for Research. By Dr. Charles 
Sedgwick Minot... 2 | 2 2. jee 
INOfES |}... uwee gece (mach Oe ae Rob 5 298 
Our Astronomical Column ;— 
WTuttle's\€omet, A. & jc ai, ee 301 
The New Comet (Barnard, July 7) ........ 301 
Astronomical Phenomena for the Week 1885, 
AUgUSti2itoS een een ois 0) eo) et ec 
Geographical Notes + ol a ol oie ot ot nO 
The Higher Mathematics. By the Editors of the 
“Acta Mathematica” .. < . . = 32). eee eeEgO? 
Dr. Perkin on the Coal TarColours........ 303 
The Devonian System of Russia , 307 
Science in Bohemia . SAP CRMs She 308 
University and Educational Intelligence . . . . . 309 
Scientific Serialsi< 08. so. . sic > - © peeaOS 
Societiesjand Academiesin a). cif) «| >) oceans 
