The foundation work of astrophysics

FRAUNHOFER, Joseph.

Bestimmung des Brechungs- und Farbenzerstreuungs- Vermögens verschiedener Glasarten.

München: Lentner, 1817.

1st Edition. Soft cover. Very Good. Item #003206

In: Denkschriften der königlichen Academie der Wissenschaften zu München für die Jahre 1814 und 1815, vol. 5, pp. 193-226, 3 engraved folding plates (2 folding). München: Lentner, 1817. 4to (270 x 230 mm), whole volume [8], xlii, 62, 226, 91 [1] pp., including half-title, general title page, 4-page index and 13 engraved plates. Original wrappers with printed spine label (little dust-soiled and spotted, spine ends slightly frayed), all pages uncut. Small worm hole in front wrapper extending into half-title without affecting text, occasional minor spotting, page edges a bit dust-soiled and frayed at lower edge, two of Fraunhofer's plates somewhat browned as usual, otherwise generally crisp and clean. Provenance: Peter and Margarete Braune (tipped-in bookplate on inner front wrapper). An exceptional, unsophisticated and wide-margined copy. ----

Dibner 153; PMM 278a; Sparrow 70; Norman 836 (offprint); DSB V, p.143. - FIRST EDITION AND OF GREAT RARITY, of a fundamental paper in astrophysics. The journal issue of Fraunhofer's milestone paper is even rarer than the offprint issue because the journal appeard in a very small print run. We can trace only two copies of the journal issue at auction in the past 30 years (Richard Green Library sale, Christies 2008, and the Norman Library Sale, Christies, 1998).
Fraunhofer, a skilled optician and designer of precision optical instruments, described in this paper, read before the Bavarian Academy in 1815, his accidental discovery of the absorption lines of the solar spectrum. In 1814, while conducting tests on the dispersion and refractive index for different kinds of optical glass, Fraunhofer "observed the effect of the refracting medium on light, comparing the effect of light from flames with light from the sun, and found that the solar spectrum was crossed with many fine dark lines, a few of which William Hyde Wollaston had observed and reported upon in 1802. [Wollaston had incorrectly interpreted the lines as borders between the colors]. Designating the more distinct lines with capital letters... he mapped many of the 574 lines that he observed between B on the red end and H on the violet end of the spectrum. Sometime later he noted that some of these lines appeared to correspond to the bright doublet of lines in many flame spectra; yet he noted further that while the pattern observed for the sun and planets [being reflected sunlight] appeared identical, the patterns for the sun, Sirius, and other bright stars differed from one another. He concluded that the lines originated in the nature of the light source. "These observations stimulated considerable interest for the next half-century among natural philosophers, whose speculations culminated in the classical explanation of absorption and emission spectra made by Kirchoff and Bunsen in 1859" (DSB). The dark lines, whose exact explanation has never been explained, are still known as Fraunhofer lines. Their discoverer continued to explore and map them during the following years; using a grating device of this own invention he eventually was able to determine the wavelengths of specific colors of light and to make highly precise measurements of dispersion (see below). Although his research was conducted with the purely practical aim of producing the finest possible optical instruments, Fraunhofer's achievements "justify describing him as the founder of astrophysics" (PMM). Plate 2, reproducing Fraunhofer's map of the lines of the solar spectrum, is the FIRST ILLUSTRATION OF THE SOLAR SPECTRUM.

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