The SciencesMay 31, 1919
Covering Power and Illuminating Power of Lenses: Tests and Performance
Stories by C. Welborne Piper
The SciencesApril 26, 1919
Photographic Permanence
The Distinction between the Print that Lasts and the Print that does Not
Covering Power and Illuminating Power of Lenses: Tests and Performance
Photographic Permanence
The Distinction between the Print that Lasts and the Print that does Not