Contains chiefly letters addressed to Ewart, although some later items of correspondence are addressed to his wife, Edith F. Ewart. There are also some instances of letters from Ewart himself to various individuals. Some key figures who feature in the correspondence are: William Bateson, Francis Hugh Adam Marshall, Arthur Balfour, Lord Arthur Cecil as well as numerous universities, societies and organisations.

Except where noted, Ewart's own replies are not present.