Beschreibung:

ANGSTRM, Anders Jonas (1814-1874). Recherches sur le spectre solaire . Uppsala: W. Schultz, 1868. 1 volume plus atlas. Text: 2 o (310 x 239 mm), lithographed frontispiece. Original brown printed wrappers. Atlas: (327 x 510 mm), 6 lithographed plates by Robert Thaln (1827-1905), Angstrm's laboratory assistant, with separate title. Unbound, laid into original brown printed wrapper (edges of wrapper worn). FIRST EDITION. Angstrm was assistant professor of astronomy at Uppsala Observatory from 1843, and professor of physics at the University of Uppsala from 1858 until his death. In 1861 Gustav Robert Kirchoff had made a map of the solar spectrum and labelled lines with the corresponding scale of his own prismatic instrument. These were considered inconvenient as each reading had to be correlated with the arbitrary Kirchoff scale. In 1868 Angstrm published this monumental work, including an atlas of the solar spectrum with measurements of the wavelengths of approximately a thousand lines determined by the use of diffraction gratings, with his results measured in units of one ten-millionth of a millimeter - a unit that was subsequently named the angstrom in his honor. Norman 56. (2)