who have children not yet protected in any way from the infection of Small Pox, to form a clear and satisfactory judgment; a judgment unbiassed by prejudice, matured by a serious and candid consideration of the evidence that will be laid before them, and on which may depend life itself, or much that renders life desirable. I have been led to believe that such an attempt may at this time prove of considerable service, in consequence of facts which have lately come under my own observation, and which have induced me to pay more attention than I had previously done to this singularly curious and interesting subject. The facts to which I allude are—1st. The prevalence of Small Pox to a considerable extent in the town and neighbourhood of Newcastle, by which a number of deaths among children, _who had not been vaccinated_, has been occasioned.—2dly. The occurrence of the disease in many individuals, who had gone through the process of Vaccination; though in every instance as far as I have been enabled to ascertain, it has been so mitigated in the violence of the attack as to preclude any degree of danger, and has never run the regular course of the genuine Small Pox.—3dly. The impression, which these occurrences have made upon the minds of those in whose families they have taken place,—an impression not only unfavourable to Vaccination, but which has induced some to entertain the idea of again having recourse to inoculation for Small Pox.—And, 4thly. The occurrence of Small Pox itself a second time in an individual, who bore ample marks of having already gone through that disease, which she stated to have taken place naturally when young: this patient was a servant in a family where three instances had occurred after Vaccination, and, as in them, the disease was of a mild and modified character. In all the cases of Small Pox after Vaccination which I have myself witnessed, or of which I have been enabled to obtain any distinct account, the disease has been of so mild a character, and so curtailed in its duration, that could it have been separated from the terrific name of _Small Pox_, it would have excited no apprehensions in the minds either of the patients themselves or of those around them. But it unfortunately happens that this disease is associated in our minds with so many terrific accompaniments (which were once indeed its constant attendants and consequences, and which belong to it in its natural form, but which, after the employment of Vaccination, have no existence whatever), that it is difficult for the mind to break through this association, and to feel satisfied that though Small Pox may still appear as an occasional visitor, yet, to the _vaccinated_, it is completely stripped of all that rendered it dangerous in its attack and serious in its effects.