An inquiry into the propagation of contagious poisons, by the atmosphere

by Somerville Scott Alison

In the case of the harvest, it would argue a forgetfulness of the object held in view when the seed was sown,—in that of disease, an ignorance of the effects to be expected from the sowing of the seeds of pestilence (the exposure to the common epidemic influences alluded to above), in the first, an insensibility to the influence of climate, intensity of sun’s rays, the quality of the soil, &c.:—And in the other, a blindness to the operation of circumstances not less potent, such as the time of application of the causes, the condition of the body, and the presence or absence of moral adjuvants.

It has universally held with all epidemic sickness, that parts of a country have been attacked in succession—that one town is visited after another, and one part of a town before another, whether the prevailing distemper have or have not been said to depend on contagion.

There is nothing extraordinary in the fact that all persons who are to suffer, do not become affected on one and the same day. Far from proving that any thing of the nature of contagion has been in operation, it only proves what may so readily be admitted, or at once readily understood, that all and sundry the inhabitants of a vast tract of country, inhabiting parts having different climates more or less mild, having different situations, some on the banks of rivers, some along the coast, some inland, some on boggy and some on dry soil; having different occupations, different houses, wearing different dresses, having different habits, different pursuits, different diet, different recreations, and perhaps having constitutions differing in aptitude to be acted upon, may not be all ready for the manifestation of disease on one and the same day, but may attain to that point at times corresponding with the operation of so many different circumstances.

In vegetation, which on the whole is much more simple than living animal organization, there is a gradation in the time at which its various individuals become ripe. The same grain is ripe in some districts weeks before it is ready in others, and even in the same farm, though the seed had been sown on the same day. Thus, by observing that the gradual development of disease over a country is the result of the varying activity and time of action of the epidemic influences, and perhaps of some condition of the body, varying in forwardness—it becomes unnecessary to have recourse to atmospheric contagion. It is unnecessary to repeat here what has been said relative to the operation of unwholesome agencies to account for the wide range of disease—over a country.

It is often said, as decisive proof of disease spreading by contagion, that a beggar, or some poor person left a town affected with disease, and entered another hitherto healthy—and that afterwards disease manifested itself there also.

In the first place, would not sickness have occurred notwithstanding? Its supporters say, not likely, when the effect followed, or immediately on the communication; but we reply, that communication took place before without any such immediate result, and that in all probability it had been going on freely all along, whatever regulation and hinderances might have been adopted.

It seems madness to think of stopping all communication with towns, in a free country such as this, where human intercourse is going on without interruption throughout the entire empire, or, indeed, anywhere at all, tolerably inhabited, or where commerce subsists.

It is in vain to endeavour to shew that opportunities for the transmission of contagious atmosphere have not occurred. The case involves an impossibility, for do not a thousand means of communication suggest themselves to the mind of the reader? The atmosphere itself, currents, winds, water, streams, &c.,—animals,—such as rats, mice, winged insects, &c. &c., which cannot be prevented from operating. We, therefore, leave this case, perhaps to the efforts of the advocates of quarantine regulations, who possibly may arrive at a happier result, and we proceed to the opposite case, where disease fails to spread, where communication does take place.

The advocates of contagion prove, where a disease appears in a town, that communication has taken place. That statement, as the reverse, can never be proven, is easily affirmed; and its insignificance corresponds with the facility with which it can be proven. Of course, it is obvious, that such a fact proves very little, either in reference to contagion or anything else.

We are prepared to prove, that communication has subsisted on many different occasions, without any unusual amount of sickness taking place. We know of many instances where disease has been prevailing in a town or village, which has failed to manifest itself in another at a short distance, although daily unrestrained communication was held.