Complex sentence: As a perceived agent of the now disgraced North Administration, Commissioner Col. Thomas Dundas rejected his claim to the promised Regius Professor ship was rejected outright in 1784, and he received only 500 pounds total compensation in 1785 for his nine years of lost salary in America.
Split into simpler sentences: As a perceived agent of the now disgraced North Administration, his claim to the promised Regius Professorship was rejected outright in 1784 by Commissioner Col. Thomas Dundas. He received only 500 pounds total compensation in 1785 for his nine years of lost salary in America.