The history of the English sweat presents to the student of epidemics much that is paradoxical although not without parallel, and much that his research can never rescue from uncertainty. Where did this hitherto unheard of disease come from? Where was it in the intervals from 1485 to 1508, from 1508 to 1517, from 1517 to 1528, and from 1528 to 1551? What became of it after 1551? Why did it fall mostly on the great houses,--on the king’s court, on the luxurious establishments of prelates and nobles, on the richer citizens, on the lusty and well fed, for the most part sparing the poor? Why did it avoid France when it overran the Continent in 1529? No theory of the sweat can be held sufficient which does not afford some kind of answer to each of those questions, and some harmonizing of them all. The history of Polydore Virgil is so well informed on all that relates to the arrival in England of Henry VII. that we may accept as the common belief of the time his two statements about the sweat, the first associating it in some vague way with the descent of Henry upon Wales, and the second pronouncing it a disease hitherto unheard of in England. Caius, who wrote in 1552 and 1555, and can have had no other knowledge of the events of 1485 than is open to a historical student of to-day, said that the sweat “arose, so far as can be known, in the army of Henry VII., part of which he had lately brought together in France, and part of which had joined him in Wales.” Hecker, the modern reconstructer of the history (1834), has passed from the tradition of Polydore Virgil and of Caius, clean into the region of conjecture in assuming that the sweat had arisen among the French mercenaries on the voyage and on the march to Bosworth. On the other hand, the one contemporary medical writer in 1485, Forrestier, is explicit enough in his statement that the sweat “first unfurled its banners in England in the city of London, on the 19th of September,” or some three weeks after Henry’s entry into the city. There is nowhere a hint that it was prevalent among the troops, whether French, Welsh or English, who won the battle of Bosworth on the 22nd of August, the only pretext for asserting that it was prevalent in the neighbourhood before the battle being the gossip of the Croyland chronicle concerning lord Stanley’s excuse to Richard III. for not bringing up his men, which gossip probably arose soon after when the sweat became notorious. Croyland was not very far from the camp of the Stanleys; and yet we know for certain (with the help of the state papers) that the death of the abbot Lambert Fossedike from the sweat happened there after an illness of eighteen hours on the 14th October, some seven or eight weeks from the date of Bosworth Field, and some three or four weeks after the outbreak of the disease in London. The probabilities of the case are all in favour of Forrestier’s view that the first of the sweat in 1485 was its appearance