&NA;He was the son of a prominant pharmacist. His early education was in the public schools, and in 1854 he graduated the youngest in his class from the College of the City of New York, then known as the Free Academy. In 1857 he earned an M.A. degree from the same institution. By clerking for his father and through contact with local physicians, he developed an interest in surgery. In 1859 he received his degree in medicine from the New York College of Physicians and Surgeons, and became a pupil and assistant to Gurdon Buck (of Buck's Extension).In 1861 he entered the Army and for most of the Civil War was in charge of the general hospital at Frederick, Maryland. He saw its capacity increase to 3,000 patients because of its proximity to the battlefields of Shenandoah, South Mountain, Antietam, and Gettysburg.Following the war, he practiced in New York City, ultimately becoming chief of the surgical service at Roosevelt Hospital. He subsequently was appointed Professor of surgery at Woman's Medical College and the College of Physicians and Surgeons.He was said to be among the most brilliant surgeons of his time. He was one of the first in the United States to adopt Lister's technique of antisepsis; he was among the early workers in brain surgery and one of the first to recognize duodenal ulcer as a pathologic entity. He was the earliest to advocate appendicostomy. His operation for carcinoma of the rectum, a more practical modification of the procedure described by Maunsell (which was recently presented in this section*) is described in the classic article here reproduced.Weir went on to become president of the American Surgical Association, New York Surgical Society, and New York Academy of Medicine. He was made an honorary fellow of the Royal College of Surgeons of England, and was one of five surgeons so honored by the American College of Surgeons at its first convocation. He died April 6, 1927, at the age of 89.