Thacher, Yale 1874; Charles B. Eddy, Yale 1893; Graham Sumner, Yale 1897; Reeve Schley, Yale 1903; and his son, Thomas Day Thacher, Yale 1904. During his forty-five years of active practice at the bar, the economic life of the country was undergoing a great transformation in the rapid development of production on a large scale. In preparing the structure of the new business organization Mr. Thacher had no small part, performing as he did, much of the legal work in connection with the organization of the Brooklyn Union Gas Company, the American Smelting & Refining Company, the Republic Iron & Steel Company, the American Sheet Steel Company, the American Steel Hoop Company, the American Can Company, the American Locomotive Company, the Railway Steel-Spring Company, and other large consolidations. He combined with such activities the work of a court lawyer, and often appeared before the courts in cases of importance. He was actively interested in the Bar Association of New York City, and for two years (1907–09) was its vice-president. From 1887 to 1914, Mr. Thacher was a lecturer on corporations in the Yale School of Law. He was a frequent contributor to the law reviews. At the Yale Bicentennial, he was chosen to deliver the address on "Yale in Relation to Law." In 1903 Yale conferred upon him the degree of LL. D. He served as president of the Yale Alumni Association in New York from 1895 to 1897 and from that time until 1904 as president of the Yale Club of New York City. At the time of his death he was an honorary member of the club. He was one of the founders of the Yale Alumni University Fund and gave himself enthusiastically to the work of the Alumni Fund Association, of which he was chairman from 1894 to 1897 and a director for many years. From 1906 until his death he was a member of the Alumni Advisory Board. Thacher was also a vice president of the University Club of New York from 1910 to 1913 and a president from 1913 to 1919. Mr. Thacher was married December 1, 1880, in New York City, to Sarah McCullough, daughter of Ashbel and Louise B. (Walker) Green, of Tenafly, who survived him with a son, Thomas Day Thacher (Yale BA 1904), and three daughters. Louise Green, who was married October 12, 1907, to Theodore Ives Driggs (Yale BA 1907);