Typed letter from Elihu Thomson to Charles F., Sr., thanking Brush for sending his fourth paper on gravitation to Thomson. Charles F. Brush, Sr., Paper Show moreTyped letter from Elihu Thomson to Charles F., Sr., thanking Brush for sending his fourth paper on gravitation to Thomson. Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 2: Acknowledgments (1921-1929) Box 3 Folder 2 Show less