2 letters, 1 handwritten 1 typed, between T. Mendenhall and Charles F., Sr., regarding Brush's inquiry about Professor C. L. Norton and a detailed dis Show more2 letters, 1 handwritten 1 typed, between T. Mendenhall and Charles F., Sr., regarding Brush's inquiry about Professor C. L. Norton and a detailed discussion of Brush's pendulum experiments and gravitation thesis. Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 3: Business and Professional (1876-1931) Box 5 Folder 4 Show less