Addison took his M.D. degree in 1815, and afterwards, it is believed, visited the Continental schools; but of this there is no certain evidence. He soon settled in London, in Skinner Street, Snow Hill, in one of the so-called haunted houses. He knew but one man, an old fellow-student, in London. Yet he received nearly sixty guineas in his first year of practice, a very considerable success. He became House Surgeon to the Lock Hospital; then Physician to the General Dispensary, where he studied skin diseases with Bateman. This appointment he held for eight years, and it was of essential service to him. He manifested a keen eye for generic distinctions and individual varieties, and might probably have succeeded to Bateman’s position in regard to skin diseases. But he was not to be made into a specialist. As Dr. Lonsdale says, “with Addison the investigation of any disease meant the full exercise of his abilities till he had mastered it, and having done this, he could not rest till he broke up fresh ground for tillage.” He dreaded becoming a specialist; it savoured of quackery. He always held that the true physician must understand surgery well; and that the good surgeon must know the principles of medicine. In 1819 or 1820 commenced Addison’s association with Guy’s. He early attracted the attention of the energetic and discerning treasurer, Mr. Harrison, then the beneficent despot of Guy’s, and was by him appointed Assistant-Physician in 1824. This was a victory for unconventional procedure, for it had always been the custom to appoint men at Guy’s who had been original pupils, and not to receive men who were already qualified and in practice into the charmed circle. It was soon evident that a great practical physician had joined the hospital staff, and he was further recognised in 1827 by receiving the lectureship of Materia Medica. Here his attractive powers were made evident by the large classes he drew around him, at a period when medical students entered for individual courses of lectures, and did not as a rule take the whole of their instruction at one school. He must have received between £700 and £800 from these lectures in some years. Men felt that he was the man to sustain and increase the fame of Guy’s.