diffraction-spectroscope

Updated: August 10, 2026

The subtle method of which they served to assure the validity was employed in 1887-9 by M. Dunér to test and extend Carrington's and Spörer's conclusions as to the anomalous nature of the sun's axial movement. His observations for the purpose, made with a fine diffraction-spectroscope, just then mounted at the observatory of Upsala, were published in 1891.

Agnes M. (Agnes Mary) Clerke - A Popular History of Astronomy During the Nineteenth Century: Fourth Edition