Happily, we are not so constituted, and the evidence that has been adduced of the narrowness of the sphere even of the most virulent contagion, shows the groundlessness of the alarm sometimes entertained respecting this dreaded agent, while it points to the certain means of destroying it. The London Fever Hospital is separated from the Small-Pox Hospital only by the space of between thirty and forty feet, and the windows of the wards of both establishments are immediately opposite each other: yet there is no instance of the communication of small-pox to the typhus patients, nor of typhus to the small-pox patients; nor of either disease to the convalescent, or to the official inmates of the adjoining establishment. There does not appear to be a single instance on record, in any country, of the extension of infection beyond the walls of an hospital, or even of a lazar-house, so as to injure in any manner the nearest inhabitants. But though it appears that modern experience and research have shed considerable light on the origin and progress of epidemic diseases, yet there are still some circumstances connected with their propagation which the present state of our knowledge does not enable us to understand, and which therefore appear to us as difficulties. These cases are sometimes termed exceptional; but they are only apparent, not real, exceptions; as in all other departments of human research, they are merely indications of the imperfection of our knowledge, and advancing science will unquestionably one day so elucidate these very exceptions, as to render them additional confirmations of the true conditions. In the present state of popular opinion it has been deemed requisite to enter into this detailed consideration of the general subject of contagion, because it appears that in proportion as undue weight is attached to this dreaded agent the effect is mischievous; since, “it diverts attention from the true source of danger, and the real means of protection, and fixes it on those which are imaginary; creates panic; leads to the neglect and abandonment of the sick; occasions great expense for what is worse than useless; and withdraws attention from that brief but important interval between the commencement and the development of disease, during which remedial measures are most effective in its cure.” It is also necessary to examine the questions of contagion and quarantine apart from each other, because there are points of obscurity, and therefore grounds for controversy, which, in the present state of our knowledge, may be reasonably considered as belonging to the former, that do not attach to the latter. The inquiry with reference to quarantine, indeed, is simple, and lies in a narrow compass. The sole question to be determined is, whether or not it accomplishes, or is capable of accomplishing, its professed object, and this is a mere question of evidence and experience.