Contains (Book 3, Cap. 2; Book 5, Cap. 4) an important account of smallpox, particularly the epidemics of 1667-69 and 1674-75. Sydenham attributed smallpox to a specific inflammation of the blood; he clearly distinguished it from measles. His treatment of fevers with fresh air and cooling drinks was an improvement on the sweating methods previously employed. English translation in his Works, ed. R. G. Latham, London, 1848, 1, 123, 219.