Thomas S. Blair of Pittsburgh died early Saturday morning at the home of a relative in that city, aged 73 years. The immediate cause of death was bronchitis, but he had been in poor health for several years. Mr. Blair, born in Kittanning in 1825, was the son of Thomas Blair, a prominent lawyer. He belonged to a pioneer family, Blair County having been named after his grandfather, John Blair, of Blair's Gap. While Thomas S. Blair was still a small boy his father died and the family removed to Pittsburgh, where he received his education in a private school. He afterward attended Harvard, graduating in the class of 1844. The year following graduation was spent by Mr. Blair in European travel, after which he became connected with the firm of G. & J. H. Shoenberger, pioneer iron manufacturers of Pittsburgh. The firm were afterward changed to Shoenberger, Blair & Co., George Shoenberger becoming senior partner and Mr. Blair taking the active part in the business. He retired from active business life about 25 years ago, having become wealthy. Mr. Blair was an authority on the scientific treatment of iron and steel, and made frequent contributions to scientific publications. He had also appeared before Congressional committees a number of times when tariff matters were under discussion. He devoted a large part of his latter years to the study of political economy. In 1896 he published a book, "Human Progress." It was the product of many years of study and observation. He was the author of other publications.