Bruce was pastor of the First Associate (United) Presbyterian Church of Pittsburgh from 1808 to his death in 1846, and was a professor of natural history, chemistry, and mathematics at the Western University of Pennsylvania from 1820 to 1843.

He was one of a class of men rarely met with: modest and retiring of manner, shunning notoriety, and averse to anything that had the appearance of ostentation.

He was highly cultured in general literature, an extensive reader, liberal minded, and a most accurate scholar in the several branches he professed.

He had the learning of a great scholar and the ability of an apt teacher; and what was no less important to his position, his dignity of manner and kindness of heart secured the love and respect of the students.

He then rented some rooms and set up a school, College Duquesne, and a number of Western University students who were members of the Tilghman Literary Society followed him.