Scientific memoirs : being experimental contributions to a knowledge of radiant energy / by John William Draper.

  • Draper, John William, 1811-1882.
Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: Scientific memoirs : being experimental contributions to a knowledge of radiant energy / by John William Draper. Source: Wellcome Collection.

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    MEMOIR IV. ON THE NATURE OF FLAME AND ON THE CONDITION OF THE SDN's SURFACE. Dove's experiments on electric light.—Dark lines replaced by bright ones. —Electric spark between metallic surfaces.—The lines depend on the chemical nature of the substance from which the light issues.—Tlieij mag be used for determining the physical condition of the sun and stars.—Three hypotheses of the condition of the sun's surface exam- ined Pao-e 81 MEMOIR V. ON THE NEGATIVE OE PKOTECTING EAYS OF THE SUN. Original discovery of protecting radiations.— Case of a daguerreotype plate.—Spectrum -photographs made in Virginia.—Protecting action of the less refrangible rays.—Protecting action of the extreme violet.— Variations of the protecting action.—Spectrum of darkness and spec- trum of daylight.—Interference of rays of different colors.—Action of waves of red, yellow, and violet light with ivave-lengths 2, 1^, 1.— Use of the diffraction spectrum 87 MEMOIR VI. ON THE DIFFRACTION SPECTRUM, Mode of obtaining the diffraction spectrum.—The yelloio is in its mid- dle ; it is a centre of cheinical action.—It is also the hottest ray,— Diffraction spectra by refection.— Cold lines.—Dilatation of the more refrangible rays in the prismatic spectrum, compression of the less re- frangible.—Action of the diffraction spectrum on salts of silver.— Use of ivave-lengths for spectrum division 9/ MEMOIR VII. STUDIES IN THE DIFFRACTION SPECTRUM. Elementary description of the diffraction spectrum.—Young's discovery of interference.—FresneVs discovery of transverse vibrations.—Gratings and the sjyectra they yield.—Gratings on refecting surfaces.—Optical action of a grating.—Its spectra of different orders.—Interpretation of wave-lengths by the mind.—Mental appreciation of multiple toave- lengths.—Refutation of the princij^le that to every color there belongs an invariable wave-length.—Increase in the range of pcrcqHion in the