XXXV. On the Reduction of Meteorological Observations; by XXXVI. Researches on Solar Physics; by WARREn De la Rue, BALFOUR STEWART, and BENJAMIN LOEWY, XXXVII. Research on the Ethers of Silicic Acid; by C. FRIEDEL XL. Partzite, a new mineral; by ALBERT ARENTS, XLI. On Contributions to Paleontology, published by the Smith- XLII. On the genus Elasmognathus; by THEODORE GILL, XLIII. On the action of water upon "Carbohydrates" at an ele. vated temperature; by O. LOEW, XLIV. Exploration of Kent's Cavern, Devonshire, Chemistry and Physics-On the conversion of dynamical into electrical force without the aid of permanent magnetism: New applications of methods of reduction in organic chemistry, BERTHELOT, 386.-On the monatomic nitriles: On graphitoid boron, Wöн- LER: On the constitution of mellitic acid, BEYER and SCHEIBLER: On the cyanic ethers, GAL, 388.-On the action of alcohols upon terchlorid of phosphorus: On the poly- mers of acetylene, BERTHELOT: New method for the preparation of oxygen, 389.-- Apparatus for detecting differences of density in transparent media, Dr. A. TÖPLER, 390.--On the atomic heat and specific gravity of gases, GUSTAV SCHMIDT, 391- Expansion of water below 4° C., Dr. WEIDNER: Specific heat of soils, L. PFAUND- LER, 393.--On the spectrum of the electrical brush and glow, A. SCHIMKOW, 394. Mineralogy and Geology.-Note on a new genus of fossil Crustacea, by F. B. MEEK, 394. --Geological Survey of Illinois, A. H. WORTHEN, 395.-On the occurrence of Eozoön in the Primary Rocks of Eastern Bavaria, by Prof. GUMBEL, 398.--A Catalogue of Offi- cial Reports upon Geological Surveys of the United States and British Provinces, 399. --Note to Article on Kaolinite, etc., by the authors, 405.-On a new specimen of Te- lerpeton Elginense, by Prof. T. H. HUXLEY, 406.-Note on Taltalite, by F. PISANI: On the punctate shell structure of Syringothyris, by F. B. MEEK, 407.--Geological Re- searches in China, Mongolia, and Japan, by RAPHAEL PUMPELLY, 408.--Nuove Osser- vazioni Geologiche sulle Rocce Anthracitifere delle Alpi, Prof. ANGELO SISMONDA : Ueber ein Equivalent der takonischen Schiefer Nordamerika's in Deutschland, etc., von Dr. H. B. GEINITZ: Note on the genus Palæaster and other Fossil Starfishes, by JAMES HALL: Descriptions of new species of Crinoidea and other fossils, by JAMES Botany and Zoology.-Catalogus Plantarum Cubensium, etc., Prof. A. GRISEBACH, 409.-- Flora Australiensis: Geographical distribution of Mammals, by ANDREW MURRAY, 410. Observations on the Genus Unio, etc., by ISAAC LEA: An Inquiry into the Zoological relations of Fossil Neuropterous Insects, by S. H. SCUDDER: On the Osteology and Myology of Colymbus torquatus, by ELLIOTT COUES: Notes on the Zygenide of Astronomy. On the Obscuration of the Lunar Crater Linné, by W. B. BIRT, 411.-- Shooting Stars in Colorado: Astronomical and Meteorological Observations at the Uni- ted States Naval Observatory, 1864, J. M. GILLISS, 413. Miscellaneous Scientific Intelligence.--Additional Gifts to Science from George Peabody, Esq., 414.--Ascent of Mount Hood, Oregon, by Rev. H. K. HINES, 416.--Meeting of the National Academy of Sciences in January, 1867: Library and Geological specimens Miscellaneous Bibliography.-A Manual of Inorganic Chemistry, by Prof. CHARLES W. ELLIOT and Prof. FRANK H. STORER, 420.--Traité des Matières Colorantes, etc., par M. P. SCHUTZENBERGER, 421.-Descriptive Astronomy, by GEORGE F. CHAMBERS, 422.--Etudes et Lectures sur l'Astronomie, par CAMILLE FLAMMARION: Weights and Measures according to the Decimal System, by B. F. CRAIG: Notices of New Works Vol. xlii, p. 271, 1. 1 and 7 from top, for H. St. Claire Deville, read F. Pisani. THE AMERICAN JOURNAL OF SCIENCE AND ARTS. [SECOND SERIES.] ART. I.-On the construction of a Normal Map of the Solar Spectrum. An abstract of a memoir read before the National Academy of Sciences, Aug. 7th, 1866; by WOLCOTT GIBBS, M.D., Rumford Professor in Harvard University. THE extraordinary impulse which has been given to the study of the spectrum by the investigations of Bunsen and Kirchhoff has led to an accumulation of details which have not yet been systematically or even conveniently arranged. To a certain extent at least this has arisen from the want of a standard map of the solar spectrum upon which new lines may be entered with precision as regards their relative places. The well known chart of Kirchhoff, though executed with great care and labor, is not, properly speaking, normal, since it only represents a spectrum formed by four flint glass prisms, the angles of which, it is true, are given, but of which the indices of refraction are not stated. Moreover the prisms were not placed accurately in the positions of least deviation for each of the spectral lines. The scale of millimeters adopted by Kirchhoff is therefore a purely arbitrary one. A standard or normal map of the spectrum must be wholly independent of peculiarities in the form of apparatus, in the number of prisms, their refractive and dispersive powers and their positions. Such a map can only be based upon the wave lengths of the spectral lines, since these do not, like the indices of refraction, vary with the material of which the prisms are composed. AM. JOUR. SCI.-SECOND SERIES, VOL. XLIII, No. 127.-JAN., 1867. The diffraction spectrum as obtained by a glass plate ruled with from one to ten thousand lines to the inch gives a nearer approach to a perfectly normal spectrum than any which has hitherto been proposed, and has been employed by Fraunhofer,* Mossottit and Draper. But even in this case there is a position of least deviation for each line depending upon the angle which the incident beam of light makes with a normal to the plane of the ruled surface, and in addition, it is necessary either to fix upon a standard number of lines to be ruled upon each millimeter of glass surface, or to reduce the positions of the spectral lines to those which would have been obtained with a standard ruled surface. We avoid all these difficulties by constructing a normal spectrum in such a manner that each spectral line shall be entered according to its wave length, a method first suggested, I believe, by Billet.§ The materials which the present condition of science furnishes for the construction of a chart of the spectrum upon the principle laid down are not very copious. They consist essentially of the older measurements of Fraunhofer of the wave lengths of the lines B, C, D, E, b, F, G and H; of recent and very accurate measurements by Angström; of a still more extended series by Ditscheiner;** of the measurements of Plückert for certain lines in the spectra of gaseous media, and of those of Esselbach ‡‡ for the ultra-violet rays. In addition we have a small number of isolated measurements by Müller, §§ Mascart,|||| Stefan, ¶¶¶ and Ketteler.* *** For the construction of the chart which I present herewith to the Academy I have selected the wave lengths determined by Angström as standards. This has been done because both the ruled glass and the measuring apparatus employed by him appear to have been much more perfect than those of other observers-Fraunhofer not excepted. On the other hand, however, all of Angström's measures are not available for the reason that the identification of the lines as produced by particular elements does not appear to be in all cases absolutely certain. As Angström's measurements are in ten-millionths of a Paris inch they have been reduced to millionths of a millimeter by multiplying them by the constant 27.07. Ditscheiner's measurements agree closely with those of Ang * Denkschr. Münch. Acad., Bd. viii, 1821-22. Annali delle Univer. Toscane, t. i, 1845; also Pogg. Ann., lxii, p. 509. L. & E. Phil. Mag., xxvi, 1845. **Sitzungsberichte der k. k. Akad. der Wiss., Bd tt Pogg. Ann., cvii, p. 497. SS Pogg. Ann., cxviii, p. 641 and cxxix, p. 637. ¶¶ Pogg. Ann., exxii, p. 634. Loc. cit. Pogg. Ann., cxxiii, p. 489. 1, 1864. Pogg. Ann., xcviii, p. 513. Pogg. Ann., cxviii, 367. *** Pogg. Ann., cxxiv, p. 390. ström after undergoing a correction which depends upon the value of the wave length of the more refrangible line of D. This value is taken by Ditscheiner as 588.8, the wave length as determined by Fraunhofer. But as, for the reasons above mentioned I consider the results of Angström more reliable, I have taken his value, 589-43, in place of that of Fraunhofer, and have reduced all the measurements of Ditscheiner in accordance with this assumption. The following table will suffice to show the agreement between the two series of measurements. A number of Ditscheiner's measurements refer to lines which cannot certainly be identified with the lines produced by particular elements. These lie between G and H and have been omitted as useless for our present purpose. But in the greater number of cases the wave lengths in his table of results are referred directly to the lines given in Kirchhoff's chart, which not merely enables us to identify them, but permits us to obtain the wave lengths of the intermediate lines by interpolation. The following table gives the corrected values of all the wave lengths measured by Ditscheiner with the exception of those between G and H, and of those of the nine principal lines of Fraunhofer which are given in Table I.* For these I have taken the values given by Angström. I have not ventured to make a further use of Angström's determinations for the reason that it is only through a comparison with the measurements of Ditscheiner that they can be identified with the lines upon Kirchhoff's scale. In every part of the spectrum excepting that between C and D the agreement between the two sets of measurements appears to fall within the limits of the errors of observation. * Marked in Table II with asterisks. |