Charles A. Young, the professor of astronomy at the College of New Jersey (later Princeton University), acquired this diffraction grating in 1878. The speculum metal plate measures 3 inches square overall, with the grating measuring 1.75 inch square. It is marked: "May 28, 1878" and "16,560 spaces" and "8648 per inch" and "Manf. by D. C. Chapman with Mr. Rutherfurd's Engine." Daniel C. Chapman was the mechanic who operated the ruling engine designed by Lewis M. Rutherfurd.
Ref. D. J. Warner, "Lewis M. Rutherfurd: Pioneer Astronomical Photographer and Spectroscopist," Technology and Culture 12 (1971): 190-216.
Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.
If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.