DR. PARKIN ON THE REMOTE CAUSE OF EPIDEMIC DISEASES.
THE object of this work is to endeavour to prove "that epidemic diseases are not only produced by volcanic action, but also that the immediate cause of their production is the generation of a poi- sonous substance in subterraneous reservoirs, and its extrication on the surface, by means of those channels which exist to a greater or less extent in all situations." Examining the various alleged causes of wide-spreading pestilences, Dr. PARKIN endeavours to prove their insufficiency ; and, referring to the facts of admitted volcanic actions in earthquakes and eruptions, he shows that they travel in right or curvilinear lines—a line of volcanoes from Chili to Mexico, for instance, "existing so uninterruptedly, that it is rare to find a degree of latitude in which there is not an active vent." An earthquake in 1827 was felt at Santa Fe da Bogota, and on the same day in a town in Siberia, propagating itself, says HUMBOLDT, in a linear direction. Touching upon the theories of Colonel REID and others on the law of storms, Dr. PARKIN asserts that the course of tornadoes is limited to the line of volcanic forma- tions; and that the whirlwind or rotatory motion, in which Colonel REID'S discovery consists, is the precise action that a gaseous emission would take. Coming down to some of the most exten- sive and fatal epidemic diseases, Dr. Perms shows that they have travelled in certain defined, and, to a mere superficial observer, arbitrary lines ; being preceded and accompanied in their more violent stages by earthquakes, whilst a general derange- ment of the seasons—great droughts, great floods, and preter- natural heat, cold, and moisture, alternating with each other—took place during the continuance of the Black Death and Cholera; the ravages of the disease bearing rather a close proportion to the severity of the volcanic action and atmospheric derangement. The escape of the poisonous substance generated "in the subterraneous reservoirs," whatever that substance be, he holds is easier on tertiary formations, such as arc the vallies of rivers, great plains, &c.; less easy on the secondary formations, consisting of uplands; and very difficult on the primitive rocks, which for the most part form the loftiest mountains : and to this circumstance he traces the respective healthiness of these different localities. The general channels by which Dr. PARKIN thinks the volcanic gases commonly escape from the subterraneous reservoirs are rivers, thermal springs, or indeed any natural outlet of water. He does not say that the poison is specific, but his view contains that conclusion ; for he holds that a different disease will be produced by the direct operation of differ- ent gases : the plague, for example, he maintains, has ceased in England, and Europe generally, not in consequence of the Fire of London, greater precautions, greater cleanliness, and the general comforts of an advancing civilization, but from the cessation of vol- canic action. In this source, too, he seems to think most cases of malaria originate; and he denies the influence of contagion in pro- pagating epidemic disease. That gases generated in the interior of the earth, and escaped through obvious volcanic vents, must have some influence upon some portion of the atmosphere, may be conceded : that great vol- canic convulsions, such as the most striking historical eruptions and earthquakes, do produce an effect upon the air within the visible extent of their operation, is matter of recorded experience, in the preternatural gloom, the oppression of the air, and various other symptoms of the sufferers : it is also probable that the action of such mighty and extensive forces as internal volcanoes operate to some degree upon the circling air of the upper earth. It its moreover true that the subject is one worth pox- suing by the natural philosopher, for its own truth, without regard to any theories connected with it ; as well as that a complete and impartial collection of all the natural pint-no- mena which have accompanied the ravages of epidemic dis- orders would be a useful work; and Dr. PARKIN may claim the merit of calling attention to both these very important subjects, as well as of urging the propriety of paying a close observation to me- teorological and other circumstances that accompany any prevalent disease. Beyond these points, the work has little striking merit. Allowing in his preface that the theory requires to be "attentively weighed and discussed," the author speaks of nearly every thing he advances as if he had established its truth ; exhibiting not only the zeal of a hobby-rider, but actually running his hobby down. So far, however, from establishing his theory, he has scarcely, with all his labour, brought it nearer probability than could have been accomplished by a simple statement of his views ; whilst he exhibits throughout a determination to bend every thing to his own notions, or a disposition to jump to conclusions, that argues either a great deficiency of logic or a very unphilo- sophical zeal. Certainty, or any thing approaching to certainty, is of course out of the question ; yet Dr. PARKIN writes as if he had proved almost every proposition be announces, though in reality the evidence on which he would establish his own theory is very much weaker than that which he holds sufficient to over- throw all other theories. Marsh effluvia, the alleged germ of malaria, has been fixed, analyzed, and the residuum found to be a rank poison to animal life : where is his poisonous substance, the result of volcanic action ? In marshy countries, the Western coast of Africa for example, the effects of the malaria are clear, certain, and constant : all foreigners exposed to its influence are affected with fever, and the majority die. Extreme volcanic action must take place continually near active volcanoes ; as Dr. PARKIN would admit had the point suggested itself to him : yet these spots are not particularly pestilential—Naples and Sicily, for example : to
some places earthquakes are so common as to be dismissed with the remark "it is a trembling"; • yet regions not volcanic are far more deadly. Several severe historical eruptions and earth- quakes have occurred, accompanied by frightful atmospheric phenomena, without being followed by pestilence ; and Dr. PARKIN
can select but two great cases in point from recorded history, the black death and the cholera; though he no doubt alludes to more epidemics, that were accompanied by phsenomena of which only loose memorials have been preserved. If one thing be the sole cause of some other thing, the effect should always follow the cause ; which is not the case with Dr. PARKIN'S theory. So far from plague and pestilence always accompanying violent volcanic action, the pestilence is almost the exception to the rule. When this great test is applied, the theory altogether breaks down. Even if this test were better borne out, the direct poisonous action would not be proved. The pestilence might be coincident with volcanic action, not caused by it. In the East, the black death and the cholera were ushered in by convulsions of na- ture, deranging the world from its depths to the utmost heights of its atmosphere. Earthquakes, heats, droughts, rains, floods, and in India preternaturally damp and moist weather, instead of the cold season, occurred ; years of great plenty preceding the outbreak and years of scarcity following them. The operation of these things upon the animal system were enough to cause severe disease,—putting the depression of natural mental anxiety and superstitious fear out of the question. The world's convul- sions might be caused by some chemical action going on in the great laboratory in the depths of the earth ; or volcanic action might be only one of several causes : in either case, if the effect upon the human frame was indirect, secondary, and operating by various means, it cannot, strictly speaking, be assigned to volcanic poison; it is almost as remote as Providence or Fate. The lines which pestilence sometimes pursues is curious—at least the opposite European circles of the black death and the cholera : the black death entered by Constantinople' slowly traversed the regions of the Mediterranean, passed through France and Britain, and thence reached Russia by Germany, Scandinavia, and Poland; whilst the cholera, entering from Russia pursued a re- verse course. Some of the author's arguments on this point, how- ever, are exaggerated if not pushed to absurdity. It is true that in desert tracks volcanic exhalations may poison the air in vain ; and if a city happen to lie in the line of march of the subterranean vol- canic poison, the mortality no doubt will be much greater on account of the dense population. It seems odd, however, that the country should often escape and cities should almost always suffer from the volcanic lines. Equally curious, that these volcanic lines should exhale a more potent venom under the low, densely-packed, dirty, comfortless abodes of the very poor ; for Dr. PARKIN in a measure precludes himself from the obvious medical explanation, by hold- ing that the venom is always equally potent in quality, though not in quantity, the ratio of mortality in those attacked being al- ways the same. Hit were desirable to treat a grave subject other- wise than gravely, we might point to the weakness of the theory urged to its extreme, when deaths are very few indeed. If the air is directly poisoned by a volcanic substance escaping from the earth, how comes it that whilst the disease exhibits its extreme virulence so few only are attacked-5,000 out of the millions of London during the whole time it prevailed ? and these not all together, but singular instances in every quarter of the town, (though predomi- nating, doubtless, in had neighbourhoods,) as if the poison had per- ception and will, and directed its spiteful course to some obnoxious persons. It is more rational to say the facts are so and so, but the causes we cannot explain, than to theorize, or rather to dogma- tize, in such fashion as this.
But be the cause of epidemic pestilences what they may, history, in despite of the theory of Dr. PARKIN, shows that their power over the human race diminishes with the advancement of mankind, and that our safety to some extent is in ourselves. Whenever epi- demics have raged, the poorest, most wretched, and most ignorant nations, have fared the worst ; and among all nations, the poor, wretched, and ignorant, are the chief sufferers. The Court of CHARLES the Second escaped the plague • the entire nation escaped the cholera: and there seems a large medical moral deducible from the narratives. Personal cleanliness, temperance and care, are in the power of every one, and greatly avail : well-drained and well- ventilated rooms are not so readily attainable, but something was done in this way at the threatened approach of the cholera, and more is promised by a Regulating Act : sufficient food, clothes, and fire, the great concomitants to air, cleanliness, and regularity, are still, unfortunately, beyond the reach of the millions ; but when we measure the present by the past, there is hope even of this in the future.
As regards literary merit, Dr. PARR IN'S book is striking in its facts, and the composition is clear and forcible. His arrangement, however, might have been more effective ; for although dividing his work into several sections for the purpose of treating different parts of his subject in an orderly succession, he does not follow out his own purpose, but mixes up different parts of the question, and sometimes repeats the same story two or three times over. The great defect of the book, however, is its tone and its want of logic. Broaching a theory which cannot at present rise higher than a probability, Dr. PARKIN constantly writes as if he were proving a positive truth ; whilst in his logic he scarcely allows that there are degrees in arguments, but makes nearly all his own conclusive—con- siders himself at liberty to assume facts when they are not recorded— and pushes his notions to such a length as to attribute the fogs of London to volcanic action, though common sense would search for their origin not in the centre of the earth, but in the sea-coal fires on the hearths of the population.