The graph displays the other subjects mentioned on the same pages as the subject “J.H. Spotts Capt. U.S.A.”. If the same subject occurs on a page with “J.H. Spotts Capt. U.S.A.” more than once, it appears closer to “J.H. Spotts Capt. U.S.A.” on the graph, and is colored in a darker shade. The closer a subject is to the center, the more "related" the subjects are.