15 typed letters between Edward Campbell and Charles F., Sr., regarding Campbell's work in magnetism, Brush's work in gravitation, and the similaritie Show more15 typed letters between Edward Campbell and Charles F., Sr., regarding Campbell's work in magnetism, Brush's work in gravitation, and the similarities between the two. Also discuss Dr. See's possibly stealing Brush's gravitation theory. 3 typed and handwritten letters from Eugenie Mereness informing Brush of Campbell's death, Brush sending sympathies to Mrs. Campbell, and Mrs. Campbell thanking Brush for his letter. Charles F. Brush, Sr., Papers Series 1: Correspondence Subseries 3: Business and Professional (1876-1931) Box 4 Folder 3 Show less