Typed letter from Samuel Mercer to Charles F., Sr., thanking Brush for sending both recent gravitation papers and promising to read both soon Charles F Show moreTyped letter from Samuel Mercer to Charles F., Sr., thanking Brush for sending both recent gravitation papers and promising to read both soon Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 2: Acknowledgments (1921-1929) Box 2 Folder 14 Show less