" The most unfavourable conclusion, therefore, that can be admitted is, that there may be the same risk of deaths from small-pox after -vaccination, as of deaths in the early stage of the inoculated small-pox. Thus, the risk is not only deferred to a later period, hut is ultimately far inferior to what it was under the use of the best inoculation previ ously to the discovery of the cow-pox, and is, in fact, re duced almost to nothing. What -more can be reasonably desired ? We do not expect to provide an absolute secu rity from all accidents." We have already stated, that since the preceding publi cation appeared, we have heard of a case of death in the se condary fever of small-pox in a patient who had been vac cinated. If such occurrences should be well authenticated, we must trust solely to the extreme dinihmtion of the gross risk as ascertained by observation, afterwards assisted by tabular statements. This still continues decidedly favour able to vaccination, as infinitely superior to the preventive by which it was preceded.
In order that this important subject may be duly im proved, the following requisites ought to be attended to. The inquirer ought to see numerous inoculations, and his observations on the progress of the disease ought to be strictly daily. He ought to inoculate with matter taken from the vesicle at various periods of its progress, all with in the limits now acknowledged to be well adapted for com municating an efficacious vaccination. He ought to ascer tain the number of successive reproductions in the human subject, to which the different specimens of matter which he uses owe their origin since they proceeded from the cow. Classifications of patients ought to be founded on these and other differences. Written accounts ought to be kept of every circumstance, even the most minute, and apparently trifling, in the past history of each patient, and in the phe nomena which occur during the progress of die disease. The aspect of his subsequent diseases, especially those of a contagious nature, as scarlatina and measles, ought to be inquired into and noted wherever it is practicable, and com parisons made in this respect between patients of different kinds. All this ought to be done simultaneously by per sons in different places, each of whom ought to be ready to take a journey on the shortest notice, in order to investi gate occasional anomalous appearances. To execute these objects on a large scale, and to provide for them men whose faithful and assiduous exertions can be relied on, till such time as satisfactory conclusions can be drawn from ample statements, might be a work of some difficulty. To
secure the daily attendance of the patients, or to visit them at their own houses when they do not attend, and to note down occurrence in the most scrupulous manner, is a task to which no man can be expected gratuitously to submit, unless his fortune is independent, his time com pletely at his command, his heart bent on the object, and his resolution much firmer than his hopes are definite. We do not see how it is practicable without the provision of a fund for the express purpose ; and, since we find that go vernments have shewn themselves not averse to appropri ate part of the revenues of nations to the great object of pre venting the contagion of small-pox, it may not be useless to remark, that their future munificence will be best be stowed on those arrangements for the attainment of the ob ject which call for the most laborious, and perhaps other wise unattainable exertions.
We shall now give a brief view of some of the most interesting collateral circumstances attending the cow pox.
This disease is not capable of being disseminated by vo latile effluvia. In this respect it differs from the inoculat ed small-pox, and exhibits one important advantage above the latter uisease, that no contagious affection is by means of it diffused through a neighbourhood.
Another circumstance is worthy of remark, that cow pox, once occurring, does not give security against a fu ture attack of the same disease. On this point different opinions have been entertained, and experiments have va ried in their results. It appears, on the whole, that by one attack of cow-pox, whether casual or as the consequence of inoculation, the susceptibility to the same disease in fu ture is only diminished. Aliikers in the dairy counties are, by passing once through it, generally able to resist the contagion iii future ; sometimes they receive it, but always in a much milder form. It is important to keep this cir cumstance in mind, because some have thoughtlessly trust ed to the effects eca second vaccination, after the first had for some time run its course, as a sufficient test of its ern, racy. That is, they have looked for an absence of future susceptibility to vaccine influence in those cases which were worthy of dependence. The influence of a previous attack of small-pox has a similar virtue. It in a slight de gree diminishes, but does net destroy, the susceptibility of the constitution to cow-pox.