English grammarian, author and politician, born in Salisbury. Educated at Salisbury and Oxford. He inherited a small fortune in 1733 upon the death of his father. In 1744 he published three treatises, to which Boswell refers in his London Journal,1 on art; on music, painting and poetry; and on happiness. In 1751 he published Hermes, a philosophical work concerning grammar. MP for Christchurch (1761-1780). Comptroller to the Queen (1774-1780). His son, James Harris (1746-1820) became 1st Earl of Malmesbury and published (1801) the complete works of his father.
Boswell met James Harris Lord Eglinton's on December 7, 1762, and May 9, 1763. He clearly knew Harris' works in advance and referred to them in his journal. He may also be the Mr Harris at whose place Boswell dined on September 12, 1769.
Searches for Title: Hermes and Author: Harris at AbeBooks yields several copies of Hermes or a Philosophical Enquiry Concerning Universal Grammar, some of them original 1751 editions, other later reprints. His treatises are much harder to come by.