Typed letter from Gratia Prouty, in charge of Western Electric Company library, to Charles F., Sr., thanking Brush for sending latest gravitation pape Show moreTyped letter from Gratia Prouty, in charge of Western Electric Company library, to Charles F., Sr., thanking Brush for sending latest gravitation paper Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 2: Acknowledgments (1921-1929) Box 2 Folder 13 Show less