tected by eudiometrical experiments. Why plague reigns and rages with all its dread malignity in this district, while the disease is unknown in that, no chemistry has yet shewn,-no eudiometer, however skilfully constructed, has hitherto detected. Even the sensible or physical and obvious qualities of the air have no direct or seeming parallel with the production of disorder, in any thing like a satisfactory combination of cause and effect;—and thus, while atmospheric change demonstrably influences the animal economy (as it does indeed the vegetable) to a large amount, the modus operandi of its influence is for the most part quite as difficult of explication as when philosophers talked of air, and earth, and water, and fire, as so many material essences.

It has long appeared to us, that some modification of electricity is at the root, as it were, of many changes and effects consequent upon aërial influence. Whoever may take the pains of remarking upon his own sensations in connection with meteorological phenomena, will find, that there is no stretch of fancy required to establish the hypothesis, that man is more or less barometrically circumstanced in reference to atmospheric electricity-more or less, we say; and the very degree, or rather the difference in degree, by which the susceptibility is marked, may in some sort be considered as proof and illustration of the principle contended for. It is those individuals who are erroneously termed nervous, who are the most sensible of the influence here adverted to. And this, it might be said, favours that doctrine which regards the link of communication between animate and inanimate being, as constituted by the electric conditions of the sentient or nervous system. The raving mad man is often more raving and more mad than ordinary, while storm and tempest are brewing in the vast magazine of circumambient space; and this fact, which in former times was deemed a proof that the nλa doo were the direct sources of maniacal paroxysms, would seem to harmonize with our present assumption.

Planetary attractions and lunar phases continued for a long time to be favourite ideas with theorists; but these notions have recently been rather scouted, and the bearings and circumstances of nervous or mental malady, have been sought for in physical or interior change, rather than in occult or exterior agency. Dr. Forster, however, seems to suppose, that we have too precipitately expelled the notion of planetary influence from our theories of madness, and that the term lunacy is not, as most of us at present imagine, too far fetched. But the reader shall have the Author's opinions in his own words.

'Atmospherical electricity, of all the phenomena of the air which

affect health, is, perhaps, the most evident. To all these we may add, as links in the chain of causes, the attraction or some other equivalent power exercised on our globe by the moon and planets, which, though not perceived by us, nor detected by instruments, is nevertheless very easily deduced from the ebb and flow of the tides; a phenomenon tending to prove by analogy, the effect which solar and lunar influence must have on all the moveable fluid matter of the earth.

It has been a popular notion time out of mind, that atmospheric changes have an influence on the state of human health. And such a belief appears to be founded on reason; for, since a number of persons of various ages, of dissimilar constitutions and habits of life, and at different places, often become the subjects of disorder at the same time, so, is it rational to attribute their malady to some general cause which then prevails: and the occurrence of disorder in particular kinds of weather, or at stated seasons of the year, which some persons experience, naturally suggests the opinion that such cause resides in the air.

But it appears to me, that it is not the heat, the cold, the dampness, or the drought of the air, which is chiefly concerned in causing disorders, nor the sudden change from one to another of these states; but that it is some peculiarity in its impregnations and in its electric state. The pain felt in limbs which have been formerly broken, and the disturbed state of the stomach of many persons before and during thunder-storms, are sufficient, I think, to warrant such a conjecture. During what has been called unhealthy weather, when other practitioners have spoken of the general ill-health of their patients, I have remarked circumstances which appeared to denote an irregular distribution of the atmospheric electricity.

But, though we admit the influence of atmospheric peculiarities on the health, yet, the manner and extent of their operation cannot be easily ascertained. They may deprive persons already weak of a portion of their electricity, and thus the energies of the brain and nervous system may be diminished; or the atmospheric electricity being unequally distributed in the air, or propagated downwards at intervals, it may occasion an irregular distribution of it in our bodies, and produce an irregularity of function."'

From this postulate of the aerial origin and modification of disorder, Dr. Forster goes on to illustrate the principle, by referring to the atmospheric influence manifested on plants and on animals; and in the course of his remarks, he alludes to the periodical tendency which Nature exhibits, when she has to do with organic functions. It will be in the recollection of those among our readers who are at all acquainted with medical literature, that Dr. Darwin and others have insisted upon the necessity of tracing these periodical dispositions, in order to gain any accurate knowledge of pathology; but the present Writer tells us, that the periodicity of nature' was first pointed out to his attention by Dr. Spurzheim. As the section which contains our Author's opinions and observations on this head, is some

what curious, and may lead others to pursue the same train of investigation, we shall extract a considerable portion of it.

I had long before', says Dr. F., ' noticed the influence of the various states of the air on the health; but I was unaware that such conditions of the atmosphere had periods within the span of human life. Dr. S. observed to me one period which excited a phenomenon of very general operation;—that for one or two days, and at the interval of twenty-seven, many persons, without any ostensible cause, and without any particular complaint, felt themselves more irritable, and less disposed for intellectual exertion, than usual. He assured me, that very irritable persons experienced a certain irritability at the half distance of time between two such periods. This remark roused my attention to the subject of periodicity in general. I observed, that it was in this manner that the great phenomena of nature are wont to unfold themselves.

The round of the seasons was one striking example; the revival of nature in spring, her maturation in summer, the fall of the leaf and the general decay of autumn, and the winter's gloomy picture of suspended life, are monuments of periodicity. Time alone appears to me not to be the cause of the phenomena of the seasons, but something which takes place at particular times. The place of our globe with respect to the sun, the grand mover of the seasons, naturally produces other secondary agents in the atmosphere wherein resides the periodical power exerted over the surface of the earth. That electricity is the principal of these agents, I have no doubt, from numerous experiments and observations which I have detailed in another place. Botanists have of late regarded the vernal rising of the sap and the growth of plants as affected by electrical causes. In proof of this, I may observe, that I have found hail and snow, so generally the vehicle of electricity, to be more conducive to early vegetation, than a warmer air, in a dry spring, or one which was attended by much unwholesome non-electric rain. The learned Abbé Bertholon goes further, and asserts, that plants growing near to conductors of atmospherical electricity, flourish better than those that are at a distance from them; and he relates one remarkable instance in France, in which some jasmine shrubs were planted against the side of a house, down the side of which was carried a metallic conductor of lightning. Of these jasmines, those which grew near the insertion of the metallic rod, acquired three times the size of the others, and extended so high as to reach the upper windows. If this be a right explanation of the disparity of size in the shrubs, those which grew by the conductor might not only have a larger share of the fluid exerted on them, but the conductor, accord-ing to the known laws of electricity, might deprive the circumjacent air, and consequently the more distant jasmines, of their natural quantity. Seasons in which there is much thunder and lightning, are the most productive of vegetable life. And the equilibrium of atmospherical electricity has been found much disturbed in seasons of epidemic pestilence. What are the remote periods of these electrical vicissitudes? Indeed, what are the great remote causes of aërial changes in general, are questions which still remain desiderata in philosophy.'

Dr. Forster has, we think, been more successful in shewing the connexion of electric impulse with organic, animal, and human existence, than in his aim to prove the periodicity, as he terms it, first suggested to him by his friend Dr. Spurzheim. We cannot help imagining, that there is a great deal taken for granted by those physiologists who advocate the regularity of function and connexion with solar, lunar, and planetary influence, which this regularity and periodicity suppose. For it appears to us, that, had there been a stable foundation upon which to erect their theories, philosophers, by this time, would have substantiated some conclusions, for the correctness of which they might have appealed to facts. At the same time, we are ready to concede, that something more than philosophy has yet dreamed of, has place both in the animate and the inanimate relations of the globe upon which we stand with the matter with which it is surrounded; and that observations, provided they keep clear of mere conjecture and the petitio principii, can never be too extended or too minute.

When discussing the topic of contagion and infection, Dr. Forster very properly draws a line of distinction between contagious and infectious diseases, the want of recognizing which, has produced considerable confusion and contradictory sentiments as to the laws which regulate the origin and spread of epidemic maladies. It is a curious fact, that modern science, with all its boasted improvements, is behind-hand with the ancients on the subject of pestilential visitation,-and partly on this account; that observers and reasoners respecting the spread of epidemic maladies, have too much overlooked the atmospherical source of distemper, and supposed the cause of all infectious maladies to be a something which, like the virus of small-pox, may be wrapped up in a pocket handkerchief, and conveyed from continent to continent. Then again, those who have opposed this principle of the importable property of infection, have erred on the other side by maintaining that a disease originally atmospheric, can never be communicated as a contagion; and have even, with more incautiousness than the contagionists themselves, flown in the face of fact, in advocating their favourite hypothesis. We must all, however, agree with the Author now under review, that the particular laws which epidemics obey, are, like other atmospheric phenomena, in'volved in much obscurity.'

Having been so long free from pestilential visitation in this part of the world, we are inclined, perhaps too presumptuously, to attribute our immunity to improvements in medical polity, and to altered habits with respect to those particulars by which plagues of various kinds were wont to be engendered and propagated; and there cannot be a doubt, that the malignancy of

febrile disorder generally, has been much mitigated by the practical application of modern science. We are cautioned, however, in a work recently published by the Poet Laureat, not to rest too secure against future invasions. The passage to which we allude, is the following.

As for famine, that curse will always follow in the train of war; and even now, the public tranquillity of England is fearfully dependent upon the seasons. And touching pestilence, you fancy yourselves secure, because the plague has not appeared among you for the last hundred and fifty years; a portion of time which, long as it may seem when compared with the brief term of mortal existence, is as nothing in the physical history of the globe. The importation of that scourge is as possible now, as it was in former times; and were it once imported, do you suppose it would rage with less violence among the crowded population of your metropolis, than it did before the Fire, or that it would not reach parts of the country which were never infected in any former visitation? On the contrary, its ravages would be more general and more tremendous, for it would inevitably be carried every where.' (All this, we remark by the way, remains to be proved.) Your provincial cities have doubled and trebled in size; and in London itself, great part of the population is as much crowded now as it was then, and the space which is covered with houses is increased at least fourfold. What if the sweating sickness, emphatically called the English disease, were to shew itself again? Can any cause be assigned why it is not as likely to break out in the nineteenth century as in the fifteenth? What if your manufactures, avoiding the ominous opinion which your greatest physiologist has expressed, were to generate for you new physical plagues, as they have already produced a moral pestilence unknown to all preceding ages? What if the smallpox, which you vainly believed to be subdued, should have assumed a new and more formidable character; and (as there seems no trifling grounds for apprehending) instead of being protected by vaccination from its danger, you should ascertain that inoculation itself affords no security?'

In a long and learned section of the work now under notice, Dr. Forster has endeavoured to connect the appearances of comets from the earliest times, with states of general sickliness, and frequently of specific or infectious disease. The following, we present as a specimen of the manner which the Author has adopted in the section to which we now refer:

1828. Comet called Encke's Comet, still to be seen: it began to approach our orbit in autumn. On Sept. 29, the remarkable zodiacal light was seen, of which an account will be found in the Essex Herald and Chelmsford Chronicle. About the same time, the pestilential fever broke out at Gibraltar, and soon afterwards lesser epidemicals appeared at Cadiz, at Paris, at Edinburgh, and other places in the outskirts of the central fever, which still prevail. See Lancet for December 1828, and January 1829. Intermittents had prevailed every where last win