Petroleum geologist. Correspondence with the Mexican Gulf Oil Company (1912–1922); Hamilton’s family correspondence (1909–1926), including some (1914) concerning the Mexican Revolution; general business correspondence (1911–1923), including some with E. L. DeGolyer; Hamilton’s geology class notes (1914–1915); Hamilton’s diary (1912–1914); printed material and reports (1913–1959) concerning oil production in Oklahoma, the Middle East, and Central and South America; and a draft of a book-length work by Hamilton, entitled “Americans in the Middle East.”