Johannes Stark Autograph Letter Signed. Three pages of a bifolium, 5.5" x 8.75", Aachen, [Germany]; December 10, 1913. Addressed to Nobel Prize winning physicist Wilhelm Wien. Written in German the year he discovered the Stark Effect for which he earned the Nobel Prize in 1919. This letter features a drawing of the Stark Effect as it applies to hydrogen as well as Stark's observations of the process. It reads in part [English translation]: "...I already collected a number of observations concerning the spectral lines of elements other than H and He, and for band lines as well. Partly they are odd, but before I share anything about this, I would like to increase the observed material in order to replace the oddities with regularities. Meanwhile, thanks to an elegant method, I was able to conclude the investigation of the longitudinal effects for H and He. As was to be expected, the congruents in the longitudinal effect are unpolarized and have the same spectral position as the congruents oscillating normally to the field in the transverse effect. The adjacent drawing gives an overview of these conditions at Hy..." Signed, "J. Stark." Condition: Smoothed creasing and mail fold. Very lightly rubbed on verso. HID03101062020 © 2020 Heritage Auctions | All Rights Reserved