Some ships, particularly the Montague and Royal Oak, had no increase of fevers or other complaints, though the one lay in port for seven, and the other for eleven weeks, and were more or less exposed to the causes of sickness which affected the rest of the fleet. This is a proof, among many others, that a particular combination of causes is necessary to produce a disease: no single one, however powerful, being sufficient, without the concurrence of others. What seemed to be wanting here was the predisposition requisite for the admission of disease into the constitution; for the ships that enjoyed this happy exemption were such as had long-established and well-regulated crews, accustomed to the service and climate. There had been this month a diminution both of the numbers and mortality of fluxes, which is agreeable to what was before remarked, that fevers were more apt than fluxes to prevail in the bad air of a harbour[16]. It was also before remarked, that there were few or no fluxes in those ships in which the fever was most malignant; and now that the fever began to grow more mild in the French prizes, the flux began to appear. In the Barfleur, Duke, and Namur, both diseases seemed to prevail equally; but the fevers, though numerous, were more of the low nervous kind than bilious or malignant; and the fluxes chiefly attacked those who were recovering from fevers. We may farther remark, that these three men of war were three-decked ships, of 90 guns, the crews of which being more numerous, and composed of a more mixed set of men, were consequently subject to a greater chance of infection, and a greater variety of complaints. The Formidable still remained healthy to an extraordinary degree. Some fevers were indeed imported from the Ville de Paris by men that had been lent to that ship, and who were taken ill after their return. Of these, a few of the worst cases were sent to the hospital, and two died on board, who, with one that died the preceding month, make the whole mortality of this ship, since leaving England, amount only to the loss of three men.