Typed postcard from W. R. Whitney to Charles F., Sr., thanking Brush for sending to Whitney a copy of the fourth paper on the kinetic theory of gravit Show moreTyped postcard from W. R. Whitney to Charles F., Sr., thanking Brush for sending to Whitney a copy of the fourth paper on the kinetic theory of gravitation by Brush Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 2: Acknowledgments (1921-1929) Box 3 Folder 7 Show less