5. Issues, setons, and blisters belong to this class of preventives of malignant and bilious fevers. Issues, according to Parisinus, Florentinus, Forestus, and several other authors quoted by Diemerbroeck, have prevented the plague in many hundred instances. Paræus says, all who had ulcers from the venereal disease, or any other cause, escaped it. Dr. Hodges owed his preservation from the plague in London, in 1665, to an issue in his leg. He says he always felt a slight pain in it when he went into a sick room. Dr. Gallaher ascribed his escape from the yellow fever of 1799 to a perpetual blister, which he applied to his arm for that purpose. Dr. Barton favoured me with the sight of a letter from Dr. James Stevens, dated January 12, 1801, in which he says he believed Dr. Beach (formerly of Connecticut) had been preserved from the bilious fever by a seton in his side. He adds further, that Dr. Beach had been called to attend the labourers at the Onandoga salt springs, in the state of New-York, ninety-eight of whom out of a hundred had the bilious fever. Of the two who escaped it, one had a sore leg, the other what is called a scald-head. The discharge from the sores in each of them, as well as from the doctor's issue, was more copious during the prevalence of the fever, than it had been at any other time. A third class of preventives of malignant fever, are such as excite a general action, more powerful than that which the miasmata are disposed to create in the system, or an action of a contrary nature. These are, 1. Onions and garlic. All those citizens who used these vegetables in their diet, escaped the yellow fever in 1793. The greater exemption of the natives of France from this disease, wherever they are exposed to it, than of the inhabitants of other European countries, has been ascribed in part to the liberal use of those condiments in their food. The Jews, it has been said, have often owed to them their preservation from the plagues which formerly prevailed in Europe. It is probable leeks and onions, which to this day form a material part of the diet of the inhabitants of Egypt, were cultivated and eaten originally as the means of obviating the plagues of that country. I have been at a loss to know why the Author of Nature, who has endowed these vegetables with so many excellent qualities for diet and medicine, should have accompanied them with such a disagreeable smell. Perhaps the reason was, kindly to force them into universal use; for it is remarkable their smell in the breath is imperceptible to those who use them.