George Loren Prince Sr. (1848-1929) was an American photographer whose studio was in Washington D.C. in the late 19th and early 20th centuries. He was commissioned to take photographs of Senators, Congressmen, Supreme Court justices, military officers, etc. He took at least one photograph of Leland Stanford that is in the Stanford University collections (item 8781).
The graph displays the other subjects mentioned on the same pages as the subject “Prince”. If the same subject occurs on a page with “Prince” more than once, it appears closer to “Prince” on the graph, and is colored in a darker shade. The closer a subject is to the center, the more "related" the subjects are.