Sydney Ringer, who died at Lastingham, in Yorkshire, on October 14, 1910, was the son of John and Harriet Ringer, of Norwich, where he was born in 1835. He was educated at private schools, and at the age of 19 entered, as a medical student, University College, London, with which institution he was to remain connected during the remainder of his active life. At the hospital connected with that school he was successively House Physician, Resident Medical Officer (1861), Assistant Physician (1863), full Physician (1866), and Consulting Physician (on his retirement in 1900); and in the Faculty of Medicine of University College he held successively the chairs of Materia Medica and Therapeutics, of Medicine and of Clinical Medicine. The School of Medicine with which Ringer was associated has produced many distinguished clinicists, but it may be safely affirmed that it has produced no better clinical teacher than the subject of this memoir. It was not, however, on the ground of his clinical reputation that Ringer was elected a Fellow of the Royal Society, and it is not in the notices of this Society that his eminence as a clinicist need be accentuated. For Ringer was more than a great physician, much as that may mean: he was a scientific enquirer. His bent in that direction showed itself early, for even while still a student of medicine he presented a paper to the Royal Society, “On the Alteration of the Pitch of Sound by Conduction through different Media,” and others to the Royal Medical and Chirurgical Society on Metabolism in Disease. These were followed by an investigation (conducted jointly with A. P. Stuart) into the diurnal variations of temperature in the human body, which was, however, not published in full until 1878. The subject of this enquiry, from its bearing on the variations of temperature in fever, never lost interest for him. But his appointment to the chair of Materia Medica and Therapeutics directed his attention towards the action of medicinal substances and agencies. His experiences of their action on the human body he embodied in his well-known ‘Handbook of Therapeutics,' of which a very large number of editions have appeared; no more thoroughly practical handbook of treatment has probably ever been written. Ringer, however, recognised that it is necessary for the understanding of the action of remedies in disease for their action in health first to be determined, and that, to comprehend their effects upon the body generally, their influence upon the individual organs and tissues must be understood. There was then no laboratory of pharmacology in London, but he found the opportunity for carrying out researches of this nature in the Physiological Laboratory of University College, where a place was always at his disposal. Here, in the intervals of a busy consulting practice, he carried out the remarkable series of researches on the action of various salts upon the tissues, and especially upon the muscular tissue of the heart, which resulted in the recognition of the influence exerted by simple inorganic constituents of the blood in maintaining the activity of the living tissues—an influence which had remained obscure, in spite of the elaborate series of researches of the same nature which were conducted in the famous Physiological Laboratory of Leipzig and elsewhere.