comparison spectra taken with Schumann plate and dry plate
Date: circa 1920
Inventory Number: 2007-1-0571
Classification: Spectrograph
Description:
A heavy piece of gray cardstock has two photographic prints of spectra glued to it. The printed captions identify one as taken with a "SCHUMANN PLATE made by ADAM HILGER, Ltd." and the other taken with an "ORDINARY DRY PLATE."
The card further states that the spectrographs were made on a "Hilger Quartz Spectrograph, Size "C," with Wave-length Scale. Source of LIght: 2 1/2 amp. Arc between Copper Electrodes, with Lithium and Barium Salts on the poles. Exposure in both cases: One Minute."