He contributed to science and academia through his 41-year term as Professor of Anatomy at the Royal College of Surgeons in Ireland (RCSI) and as the first Irish ocular pathologist.

In 1826 he was elected Professor of Anatomy and Physiology at Royal College of Surgeons in Ireland (RCSI), and held the chair until 1869.

His younger rival, Sir William Wilde, subsequently founded the competing St. Mark's Ophthalmic Hospital in Lincoln Place (beside Trinity College) in 1844.

In December 1860 a medal bearing Jacob's likeness was struck and presented to him, and his portrait, bust, and library were later placed in the Royal College of Surgeons in Ireland.

In 1819 Jacob announced the discovery, which he had made in 1816, of a previously unknown membrane of the eye, in a paper in the Philosophical Transactions (pt.

His major publications included: In 1824 Jacob married Sarah, daughter of Coote Carroll, of Ballymote, County Sligo.