Brooke was described as "a young gentleman" with "an interest in the blacks and talks their language fluently." See: https://espace.library.uq.edu.au/data/UQ_246256/Qld_heritage_v2_no4_1971_p26_p38.pdf
The graph displays the other subjects mentioned on the same pages as the subject “Jocelyn Brooke”. If the same subject occurs on a page with “Jocelyn Brooke” more than once, it appears closer to “Jocelyn Brooke” on the graph, and is colored in a darker shade. The closer a subject is to the center, the more "related" the subjects are.