1. There is often an interval of from two to ten years, between the sickness and deaths which occur in families from consumptions, and this we know never takes place in any disease which is admitted to be contagious. 2. The consumption is not singular in affecting several branches of a family. I was lately consulted by a young physician from Maryland, who informed me, that two of his brothers, in common with himself, were afflicted with epilepsy. Madness, scrophula, and a disposition to hæmorrhage, often affect, in succession, several branches of the same family; and who will say that any one of the above diseases is propagated by contagion? The practice of the Spaniards and Portuguese, in burning the clothes of persons who die of consumptions, no more proves the disease to be contagious, than the same acts sanctioned by the advice or orders of public bodies in the United States, establish the contagious nature of the yellow fever. They are, in both countries, marks of the superstition of medicine. In suggesting these facts, and the inferences which have been drawn from them, I do not mean to deny the possibility of the acrid and f[oe]tid vapour, which is discharged by breathing from an ulcer or abscess in the lungs, nor of the hectic sweats, when rendered putrid by stagnating in sheets, or blankets, communicating this disease to persons who are long exposed to them, by sleeping with consumptive patients; but that such cases rarely occur I infer, from the persons affected often living at a distance from each other, or when they live under the same roof, having no intercourse with the sick. This was the case with the black slaves, who were supposed to have taken the disease from the white branches of a family in Connecticut, and which was mentioned, upon the authority of Dr. Beardsley, in a former edition of this inquiry. Admitting the above morbid matters now and then to act as a remote cause of consumption, it does not militate against the theory I have aimed to establish, for if it follow the analogy of common miasmata and contagions, it must act by first debilitating the whole system. The approach of the jail and bilious fevers is often indicated by general languor. The influenza and the measles are always accompanied by general debility, but the small-pox furnishes an analogy to the case in question more directly in point. The contagion of this disease, whether received by the medium of the air or the skin, never fails of producing weakness in the whole system, before it discovers itself in affections of those parts of the body on which the contagion produced its first operation.