The small-pox, though a disease of less force than the plague, has often chased it from Constantinople, probably from its being in a declining state. But this exclusive prevalence of a single epidemic is not confined to the plague and small-pox. Dr. Sydenham's writings are full of proofs of the dominion of febrile diseases over each other. Hence, after treating upon a symptomatic pleurisy which sometimes accompanied a slow fever, in the year 1675, and which had probably been injudiciously treated by some of those physicians who prescribe for the name of a disease, he delivers the following aphorism: "Whoever, in the cure of fevers, hath not always in view the constitution of the year, inasmuch as it tends to produce some particular epidemic disease, and likewise to reduce all the cotemporary diseases to its own form and likeness, proceeds in an uncertain and fallacious way[34]." It appears further, from the writings of this excellent physician, that where the monarchy of a single disease was not immediately acknowledged, by a sudden retreat of all cotemporary diseases, they were forced to do homage to it, by wearing its livery. It would be easy to multiply proofs of this assertion, from the numerous histories of epidemics which are to be found in his works. I shall mention only one or two of them. A continual fever, accompanied by a dry skin, had prevailed for some time in the city of London. During the continuance of this fever, the regular small-pox made its appearance. It is peculiar to the small-pox, when of a distinct nature, to be attended by irregular sweats before the eruption of the pock. The continual fever now put on a new symptom. It was attended by sweats in its first stage, exactly like those which attended the eruptive fever of the small-pox[35]. This despotism of a powerful epidemic extended itself to the most trifling indispositions. It even blended itself, Dr. Sydenham tells us, with the commotions excited in the system by the suppression of the lochia, as well as with the common puerperile fever[36]. Dr. Morton has left testimonies behind him, in different parts of his works, which establish, in the most ample manner, the truth of Dr. Sydenham's observations. Dr. Huxham describes the small-pox as blending some of its symptoms with those of a slow fever, at Plymouth, in the year 1729[37]. Dr. Cleghorn mentions a constitution of the air at Minorca, so highly inflammatory, "that not only tertian fevers, but even a common hurt or bruise required more plentiful evacuations than ordinary[38]." Riverius informs us, in his history of a pestilential fever that prevailed in France, that "it united itself with phrenitis, angina, pleurisy, peripneumony, hepatitis, dysentery, and many other diseases[39]." [34] Vol. i. p. 340. [35] Vol. i. p. 352. [36] Vol. ii. p. 164. See also p. 1, 109, 122, 204, 212, 233, 274, 355, 358-9, and 436. [37] De Aere et Morb. Epidem. p. 33, 34. [38] Page 285.