Recherches sur le Spectre Solaire. [With:] Spectre normal du soleil. Atlas de six Planches.

Upsalla: W. Schultz, 1868.

First edition, a very fine copy in unrestored original printed wrappers, and rare thus, of one of the founding works of spectroscopy in which Ångström demonstrated the presence of hydrogen and a number of other elements in the sun; the atlas contains his great map of the solar spectrum. Since the plates of the atlas were simply laid in to the printed wrappers (and not sewn), the wrappers were often lost or damaged; it is rare to find these wrappers present and in fine condition as in our copy. In his Nobel Prize lecture, Arthur Schawlow (who shared the 1981 prize for his contributions to the development of laser spectroscopy) wrote: “Fraunhofer had charted the dark lines in the spectrum of the Sun, and had measured their wavelengths. But it was Ångström who first identified some of these lines as corresponding to bright lines emitted by particular substances … Most importantly, he showed the red line of hydrogen.” “After 1861 Ångström intensively studied the spectrum of the sun, noticing the presence of hydrogen in the solar atmosphere and confirming the probable existence there of a number of other elements. In 1868 he published the monumental Recherches sur le Spectre Solaire, which contained an atlas of the solar spectrum with measurements of the wavelengths of approximately a thousand lines determined by the use of diffraction gratings. Ångström expressed his results in units of one ten-millionth of a millimetre – a unit of length that has been named the Ångström unit in his honor. In order to have a precise basis for the new science of spectroscopy, accepted standards were needed … In 1861 Kirchhoff made a map of the solar spectrum and labeled lines with the corresponding scale readings of his own prismatic instrument. These rapidly became the almost universally accepted manner of designating spectral lines, but they were inconvenient because each observer had to correlate his own readings with those of the arbitrary Kirchhoff scale. Ångström’s wavelength measurements provided a more precise and convenient reference and, after 1868, became a competing authoritative standard” (DSB). Spectroscopic studies were crucial to Max Planck’s explanation of blackbody radiation, Albert Einstein’s explanation of the photoelectric effect, and Niels Bohr’s explanation of atomic structure. Spectra are used to detect, identify and quantify information about the chemical composition of substances in the laboratory, as well as in astronomy where they enable the determination of the chemical composition and physical properties of celestial objects.

“By the time that Ångström began his studies on spectral analysis at Uppsala, a fair amount of information was known, more experimentally than theoretically, about the solar spectrum. Optics had become a subject of intensive study during the first half of the nineteenth century, but there was little interest in identifying the cause of the lines on the spectra and in appreciating their structural implications … no significant progress had been made in the eighteenth century since Newton’s classic investigations on sunlight and his experiments with prisms and reflecting telescopes … Newton failed to note that the light from the sun is not perfectly homogeneous; instead it was [William Hyde] Wollaston (1766-1828) who first discovered this effect by observing the rays of sunlight admitted through a narrow slit in a window blind. Wollaston’s initial observation of seven dark lines, followed by [Joseph von] Fraunhofer’s work, which included a greater number of lines in the solar spectrum, lies at the root of all subsequent works, including that of Ångström. The studies of these pioneers had shown that whereas sunlight differed from ordinary white light in having a spectrum of dark lines, colored light differed from the same white light in having a spectrum in which bright lines could be seen. Ångström familiarized himself with all of this work …” (Reif-Acherman).

“By the time he was appointed regular professor of physics, in 1858, Ångström had already published one of his two most famous contributions to the new scientific field of spectroscopy. The paper Optical Researches was published in Swedish in 1853 and in English and German two tears later. In it Ångström presented, in an unsystematic fashion, a number of experimental results concerning the absorption of light from electrical sparks in gases. He also made theoretical interpretations indicating, among other things, that gases absorb light of the same wavelengths that they emit when heated, and suggesting, somewhat obliquely, that the Fraunhofer lines could be explained in this way.

“During the priority disputes that followed Gustav Kirchhoff’s publication of the law of absorption and the explanation of the Fraunhofer lines [and his map of the solar spectrum] around 1860, Ångström and his collaborator at Uppsala University, Robert Thalén (1827-1905), vigorously defended the Swede’s priority. Their claims were to some extent recognized also in Britain when the Royal Society elected Ångström foreign member in 1870 and awarded him the Rumford Medal two years later. These honors were also given in recognition of Ångström’s other important spectroscopic work, an atlas of the solar spectrum published in 1868” (Biographical Encyclopedia of Astronomers).

“In 1868, Ångström published his most important work, ‘Recherches sur le Spectre Solaire’, in Uppsala. The essay, a compendium of all of his experiments, received considerable international attention and became the standard of spectroscopy for at least a quarter of a century … Because of its considerable greater dispersive power [i.e., that of Ångström’s spectrometer], the information included in Ångström’s map surpassed the information found in Kirchhoff’s map, and the number of visible bands rose accordingly … Several dark bands on Kirchhoff’s map resolved themselves into arrays of tightly packed lines … The measurements give the places of and map the solar lines in … the entire visible spectrum, and the wavelengths are expressed in ten-millionths of a millimetre with two decimal places. Each line was rendered in ink as it appeared to the eye, with coloration that ranged from pale grey to coal black. The work included an atlas of close to a thousand spectral lines, with, for example, 390 more iron-lines than were previously known” (Reif-Acherman).

“For this work a high quality spectrometer with collimator and viewing telescope manufactured by the Berlin firm of Pistor and Martins was used. The prism was replaced with a transmission [diffraction] grating ruled by F. A. Norbert, of which Ångström had two available, with respectively 4501 and 2701 grooves ruled in glass … Ångström calibrated his wavelength scale by carefully measuring nine principal solar lines, using measurements in several orders of diffraction … Over 1000 solar lines were measured and tied to this scale” (Hearnshaw, p. 102). Ångström’s spectrometer is illustrated on the frontispiece of the text volume of the present work.

“The gratings were measured with a dividing engine, which allowed Ångström to determine the grating space by comparison with the standard meter possessed by the Uppsala Institute … Certain doubts that Ångström had about a major systematic error [that had] crept into his work, as a result of calibrating his meter, were confirmed years later. In 1872, Georg Lindhagen (1819-1906) checked several meter standards and found that the earlier calibration of the Uppsala meter was incorrect, having a length of 999.94 mm instead of the 999.81 mm used by Ångström in his measurements. This deviation resulted in a clear systematic error of approximately 0.013% in all of the wavelengths previously measured. Ångström did not rush to revise his work, perhaps because he never thought that the differences in wavelengths regarding this error were as significant as were later confirmed, and he only commissioned this labor to his assistant Thalén in 1874. Ångström unexpectedly died that year with the calculations scarcely begun, leaving this problem unresolved” (Reif-Acherman).

“Anders Ångström(1814-1874) was an astronomical observer, physicist, and a pioneer in spectroscopy. His father Johan was a clergyman in the Lutheran church of Sweden. Ångström and his two brothers, Johan and Carl, all received higher education. Carl became a professor of mining technology; Johan became a physician and well-known botanist. Ångström studied at Uppsala University, and in 1839 he became a docent in physics there. As the professor in physics was a fairly young man, and as there were no other academic positions in physics other than the professorship, Ångström switched to astronomy, where there was a position as astronomical observer at the university.

“During the 1840s and 1850s Ångström worked as astronomical observer and acting professor of both astronomy and physics at Uppsala University. He did research in various fields during these years, for example in geomagnetism and the heat conduction of metals …

“During the 1860s and 1870s Ångström and Thalén carried out a great number of spectroscopic measurements, not only on the Fraunhofer lines but also on the wavelengths of emission spectra of many substances. During these decades and into the early 1880s, Ångström and Thalén dominated European spectroscopy. A measure of their influence is the publication of lists of spectroscopic data for the elements carried out by the British Association for the Advancement of Science [BAAS] in the mid-1880s. Of 67 elements, measurements by Ångström and Thalén (mostly by the latter) were given for 60; no other spectroscopists came close to that figure …

Ångström became a member of the Royal Swedish Academy of Sciences in 1850, of the Prussian Academy of Sciences in 1867, of the Royal Society in 1870, and of the French Academy of Sciences in 1873. He was elected a member of several other Swedish and foreign scientific societies as well.

“In 1845 Ångström married Augusta Bedoire, and they had four children, two of whom survived to adulthood. Their son Knut became a professor of physics at Uppsala University, succeeding his father’s successor Robert Thalén in 1896. Their daughter Anna married Carl Gustaf Lundquist, a student of her father's, who in 1875 succeeded Thalén as professor of theoretical physics. There were additional family ties between the Ångströms and other scientific families at Uppsala. Hence, Anders Ångström was a founder not only of the science of spectroscopy but also of a scientific dynasty” (Biographical Encyclopedia of Astronomers).

It is sometimes said that a few copies of the atlas have a further two plates showing the ultraviolet spectrum (although the title of the atlas clearly states Atlas de six Planches). All copies we have located in auction records have only six plates, except for a presentation copy offered by Sotheby’s, Paris in 2011, described as “Exemplaire bien complet de l’Atlas auquel sont ajoutées deux planches figurant le spectre de l’ultra-violet, d'après A. Cornu.” These extra plates do not belong to the work but were added later from Cornu’s ‘Sur le spectre normale du soleil, partie ultra-violette’, Annales Scientifiques de l’École Normale Supérieure, Sér. 2, T. 9 (1880), pp. 21-106, which included two plates of the ultraviolet spectrum. “The French scientist Marie Alfred Cornu (1841-1902), chair of physics at the École Polytechnique, extended Ångström’s atlas to the ultraviolet with comparable accuracy by using photographic methods and similar diffraction gratings” (Reif-Acherman).

DSB I, p. 166; Norman 56; Honeyman 96. Hearnshaw, Astronomical Spectrographs and their History, 2009. Reif-Acherman, ‘Anders Jonas Ångström and the foundation of spectroscopy – Commemorative article on the second centenary of his birth,’ Spectrochimica Acta, Part B, vol. 102 (2014), pp. 12-23.

Text: Large 4to, pp. [iv], 42, xv, [1], with lithographed frontispiece showing Ångström’s spectrometer; Atlas: Oblong folio, [ii], with six plates by Robert Thalén (1827-1905). Original brown printed wrappers. Both in exceptionally fine condition.

Item #4831

Price: $8,500.00