 In 1882 he married Sarah Katherine Wills, daughter of William Ridout Wills, the brother of judge Sir Alfred Wills.In 1883, still in his twenties, Jones became the first principal of the University College of South Wales and Monmouthshire (afterwards Cardiff University) and the head of its Physics Department.At the same time he became principal of the Cardiff Technical School (forerunner of the University of Wales Institute of Science and Technology (UWIST)).