Under the able investigation of Dr Haygarth, the doctrine of infection has been deprived of much of its extravagant character. Under his examination it is found losing that widely extended range of action, and that extreme virulence, that had hitherto marked its history. Dr Bateman, in his excellent work on contagious fever, after alluding to a prevalent opinion, that contagious poison is capable of diffusion in the air, says, “To one acquainted with the evidence which has been adduced relative to the properties of contagion, these opinions, and the terrors connected with them, appear equally unfounded and absurd, as are all creations of an over-excited imagination magnified by prejudice and alarm—for it has been proved, beyond the possibility of a doubt, by the concurrent testimony of a multitude of the ablest practitioners, who have had every opportunity of investigating the fact, and by all the experience which the establishment of fever boards and houses of recovery has afforded the means of accumulating, that no contagion whatever is communicable, even to the distance of a few feet, through the medium of the free and open atmosphere, and consequently that residence in a district where fever prevails is free from all danger. Nay, it has been further proved on the same undeniable evidence, that the house and even the apartment, occupied by the sick, may be rendered perfectly innocuous, the contagion being disarmed of its activity and virulence by dilution with pure air,” &c. Dr Bateman gives the following facts— “All the patients admitted into the London House of Recovery are transported in a litter by two others employed by the institution, enveloped in their uncleanly and tainted apparel. Yet the porters who have been daily occupied for the last eighteen months in conveying this double source of contagion, often the distance of two or three miles, and assisting them in and out of the litter, have never received the infection. “Neither have the washerwomen, employed during the period of my attendance, (sixteen years) on the House of Recovery, occupied almost constantly in washing the apparel brought in by the patient, as well as the bed-linen, often much soiled by their excretions, and the cloths used by the patients in the house, ever been affected with the fever.” Dr Patrick Russell, whose work on the plague is so well known, is the next writer to whose observations reference will be made. His personal observation of much contagious disease, and his high character, entitle his observations to much weight. They will amply shew, how the question before us has gained with the advancement of medical science. Some are subjoined.