Typed letter from Thomas Perry to Charles F., Sr., thanking Brush for sending his latest gravitation paper, remarking on the boldness of challenging N Show moreTyped letter from Thomas Perry to Charles F., Sr., thanking Brush for sending his latest gravitation paper, remarking on the boldness of challenging Newton and also the necessity not to simply trust a great name with some examples of why Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 2: Acknowledgments (1921-1929) Box 2 Folder 14 Show less