Scientific Serials | Nature

ABSTRACT _Wiedemann's Annalen der Physik und Chemie_, No. 8 (1893).—Polarisation of undiffracted infra-red radiation by metal wire gratings, by H. E. J. G. du Bois and H. Rubens.

Polarised light passing without diffraction through silver wire gratings experiences in general a rotation of its plane of polarisation. The transmitting power of the gratings for light

polarised in a plane perpendicular to the length of the wires was found to be greater than that for light polarised in a plane parallel to them. The present, experiments were conducted with

finer gratings than before the smallest interval attained being 0˙001 cm. and the measurements were taken in the infra-red region. The intensity of radiation transmitted was measured by the

bolometer. It was found that as long as the wave length does not exceed a certain value, the grating transmits a larger fraction of the radiation when the electric vector is parallel to the

wires; this value appears to be independent of the width of interval, but characteristic of the metal; for greater wave-lengths the transmittance is greater when the magnetic vector lies in

the direction of the wires.—The superior limit of wave-lengths which may occur in the thermal radiation of solids; a conclusion from the second law of thermodynamics, by Willy Wien. Assuming

the second law, and the existence of none but Maxwell's ponderomotor forces in the pressure exerted by a gas, the author shows that thermal radiation does not imply waves of all

lengths, but that the curve of energy, when traced along the spectrum, falls continuously to infinitesimal values on the less refrangible side, and practically disappears in the region of

Hertz's finite waves.—Electric oscillations of molecular structures, by H. Ebert. It is shown that the mechanism of luminescence may be fully explained by Maxwell's theory,

regarding the luminous molecules as analogous to Hertz oscillators of very small dimentions.—A photometer, by E. W. Lehmann. This is constructed on the principle of Joly's photometer;

it consists of two totally reflecting prisms placed side by side in a box. In each prism one of the adjoining faces is ground, and the two ground faces are turned in opposite directions so

as to be illuminated by the two sources to be compared. The plain faces are turned towards the observe, with their edges touching. The observer looks at them through a tube containing a

telescope; the box to which the tube is attached can be swung round through 180°, so as to exchange the ground faces. The sensitiveness is such that forty successive readings with amyl

acetate burners at 120 cm. gave results not differing by more than 0˙4 per cent. Access through your institution Buy or subscribe This is a preview of subscription content, access via your

institution ACCESS OPTIONS Access through your institution Subscribe to this journal Receive 51 print issues and online access $199.00 per year only $3.90 per issue Learn more Buy this

article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which are calculated during checkout ADDITIONAL ACCESS OPTIONS: * Log in

* Learn about institutional subscriptions * Read our FAQs * Contact customer support RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Scientific Serials.

_Nature_ 48, 406 (1893). https://doi.org/10.1038/048406b0 Download citation * Issue Date: 24 August 1893 * DOI: https://doi.org/10.1038/048406b0 SHARE THIS ARTICLE Anyone you share the

following link with will be able to read this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard Provided by the Springer

Nature SharedIt content-sharing initiative