Thus did America receive this great discovery, destined to save thousands of lives, via Boston, from the hands of one of our own Massachusetts physicians. The year 1735 was rendered sadly memorable by the epidemic of the terrible disease known as “throat distemper,” and regarded by many as the same as our “diphtheria.” Dr. Holyoke thinks the more general use of mercurials in inflammatory complaints dates from the time of their employment in this disease, in which they were thought to have proved specially useful. At some time in the course of this century medical practice had settled down on four remedies as its chief reliance. I must repeat an incident which I have related in another of these Essays. When Dr. Holyoke, nearly seventy years ago, received young Mr. James Jackson as his student, he showed him the formidable array of bottles, jars, and drawers around his office, and then named the four remedies referred to as being of more importance than all the rest put together. These were “Mercury, Antimony, Opium, and Peruvian Bark.” I doubt if either of them remembered that, nearly seventy years before, in 1730, Dr. William Douglass, the disputatious Scotchman, mentioned those same four remedies, in the dedication of his quarrelsome essay on inoculation, as the most important ones in the hands of the physicians of his time. In the “Proceedings” of this Society for the year 1863 is a very pleasant paper by the late Dr. Ephraim Eliot, giving an account of the leading physicians of Boston during the last quarter of the last century. The names of Lloyd, Gardiner, Welsh, Rand, Bulfinch, Danforth, John Warren, Jeffries, are all famous in local history, and are commemorated in our medical biographies. One of them, at least, appears to have been more widely known, not only as one of the first aerial voyagers, but as an explorer in the almost equally hazardous realm of medical theory. Dr. John Jeffries, the first of that name, is considered by Broussais as a leader of medical opinion in America, and so referred to in his famous “Examen des Doctrines Medicales.” Two great movements took place in this eighteenth century, the effect of which has been chiefly felt in our own time; namely, the establishment of the Massachusetts Medical Society, and the founding of the Medical School of Harvard University. The third century of our medical history began with the introduction of the second great medical discovery of modern times,--of all time up to that date, I may say,--once more via Boston, if we count the University village as its suburb, and once more by one of our Massachusetts physicians. In the month of July, 1800, Dr. Benjamin Waterhouse of Cambridge submitted four of his own children to the new process of vaccination,--the first persons vaccinated, as Dr. Zabdiel Boylston's son had been the first person inoculated in the New World.