is called from its origin the _Jail Fever_, is evidently the offspring of filth and deficient ventilation. The Lord Chancellor _Bacon_ has made the following observation upon this subject: “The most pernicious infection next to the plague is the smell of the jail, where prisoners have been long, close, and nastily kept; whereof we have had, in our time, experience twice or thrice, when both the judges that sat upon the jail, and numbers of those who attended the business, or were present, sickened upon it, and died.”[205] Dr. Bancroft, who has dwelt very fully upon the subject of jail fever,[206] considers it as a species of typhus, the contagious essence of which is not generated, but merely lighted up by the filth of prisons. IV. _Can a Fever produced by fatigue, unwholsome food, &c. be rendered contagious in its career by animal filth, impure air, &c.?_ We have no hesitation in answering this question in the affirmative, and our opinion will receive ample support from the history of the different epidemic fevers which have raged in our own times. Dr. _Prichard_[207] is persuaded that a contagious fever may have a spontaneous origin, that is, that the ordinary sources of derangement may occasion such a kind of disordered action, that the excretions or effluvia from the subject of it shall, under certain circumstances, produce a specific effect upon another. The truth of this position is amply confirmed by comparing the different phenomena which, according to Dr. _Prichard_,[207] are displayed by the epidemic in St. Peter’s Hospital, and the Bristol Infirmary; in the former house the medical wards are very small, having been originally destined, not for the accommodation of the sick, but for the abode of paupers; in consequence of which it became necessary to place the beds very near to each other, and to crowd the rooms with patients; under these circumstances the disease was manifestly contagious, while in the well-ventilated Bristol Infirmary, notwithstanding the indiscriminate manner in which the patients with fever were scattered through the wards, not a single instance occurred of its propagation. The Dublin Reports of Drs. _Grattan_[208] and _Crampton_[209] are equally satisfactory upon this question; atmospheric vicissitudes, intemperance, fatigue, suppressed perspiration, the depressing passions, &c. when excessive, will induce fever; and under these circumstances, the accumulation of animal effluvia, in filthy, crowded, and ill-ventilated dwellings, will generate contagion, which of course accelerates the march of the epidemic.