<span>Typed letter from Warren J. Brodie from Charles F. Brush, Sr., with Brodie thanking Brush for sending him the third paper on Gravitation, and suggesting </span><span>another experiment with kinetic energy in terms of heat units.Charles F. Brush, Sr., PapersSeries 1: CorrespondenceSubseries 2: Acknowledgments (1921-1929)Box 3Folder 1</span>