[14] I have once known this breath, in a gentleman who had carried the seeds of the yellow fever in his body from Philadelphia into its neighbourhood, create sickness at the stomach in his wife; and I have heard of an instance in which a person, who left Philadelphia when highly impregnated with the miasmata of the same fever, creating sickness at the stomach in four or five persons who sat at the same table with him in the country. None of the above persons were afterwards affected by the fever. In an anonymous history of the plague in London, in the year 1664, in the possession of the author, it is said, the breath was a well-known signal of infection to persons who were not infected, and that whenever it was perceived, individuals and companies fled from it. The sickness in the above-mentioned persons was similar to that which is sometimes excited by the smell of a sore leg, or a gun-shot wound, upon the removal of its first dressing. It does not produce fever, because there is no predisposition to it. The means of preventing the different forms of our summer and autumnal disease come next under our consideration. I shall first mention such as have been most effectual in guarding against its malignant form, and afterwards take notice of such as are proper in its milder grades. These means naturally divide themselves again, I. Into such as are proper to protect individuals. II. Such as are proper to defend whole communities from the disease. And, III. Such as are proper to exterminate it, by removing its causes. I. Of the means of protecting individuals. Where flight is practicable, it should be resorted to in every case, to avoid an attack of a malignant fever. The heights of Germantown and Darby have, for many years, afforded a secure retreat to a large number of the citizens of Philadelphia, from their late annual epidemics. It were to be wished our governments possessed a power of compelling our citizens to desert the whole, or parts, of infected cities and villages. In this way the yellow fever was suddenly annihilated in Providence, on Rhode-Island, and in New-Haven, in Connecticut, in the year 1805. But the same power should rigorously prevent the removal of the sick, except it be that class of them which have neither homes nor friends. The less the distance they are carried beyond the infected atmosphere, the better. The injury sustained by conveying them in a jolting carriage, for two or three miles, has often been proclaimed in the reports of our city hospitals, of patients being admitted without a pulse, and dying a few hours afterwards. In leaving a place infected by miasmata, care should be taken not to expose the body to great cold, heat, or fatigue, for eighteen or twenty days, lest they should excite the dormant seeds of the disease into action.