But, as soon as we begin to apply this formula to particular historic cases, difficulties and ambiguities arise[773]. To come back to the instance of Jamaica in 1692, did the general sickness of the island, manifestly miasmatic as it was, and due to disturbances of soil, become an influenza for other regions of the globe? About fifteen months after there was, indeed, a universal catarrh in Britain and Ireland, of no great fatality, which is said by Molyneux, of Dublin, to have prevailed also in the northern parts of France, Flanders, and Holland, but is not reported in the usual way from Europe generally nor from America. Let us suppose a miasmatic cloud formed over the island of Jamaica in June, July, August and September, a cloud of infective particles which might produce influenza at a distance from its place of origin, whatever disease the miasmata after the earthquake may have produced in Jamaica itself. Let this invisible cloud, or emanation, get into the warm atmosphere over the great oceanic current that sets out from the Gulf of Mexico. The vehicle lies ready to hand,—to receive the miasmata not far from their place of origin, to carry them far into the Atlantic, and to bring them, perhaps, to the shores of Britain. This may seem a sufficiently plausible source of the influenza of October and November, 1693, which appears to have been felt only in the British Isles and on the opposite shores of the North Sea. But Webster’s own choice is the volcanic eruption in Iceland in the same year as the influenza; and if we prefer, in this hypothesis, an earthquake to an active volcano, there is a rival source for the British influenza of 1693, nearer both in place and time than that of Jamaica in 1692, and not less important in respect of miasmatic disease in its own locality. This was the disastrous series of earthquakes in Calabria and Sicily, culminating on the 9th of January, 1693. The following extracts from the account sent to the Royal Society will show how great was the commotion of soil, of underground water, and of atmosphere, and how close the connexion of these with the sickness ensuing[774]:

“In the plain of Catania, an open place, it is reported that from one of the clefts in the ground, narrow but very long and about four miles off the sea, the water was thrown forth altogether as salt as that of the sea, [as in Jamaica the year before]. In Syracuse and other places near the sea, the waters in many wells, which at first were salt, are become fresh again.... The fountain Arethusa for the space of some months was so brackish that the Syracusans could make no use of it, and now that it is grown sweeter the spring is increased to near double. In the city of Termini all the running waters are dried up.... It was contrary with the hot-baths, which were augmented by a third part.

Darkness and obscurity of the air has always been over us, but still inferior to that on the 10th and 11th of January; and often these clouds have been thin and light, and of a great extent, such as the authors call rarae nubeculae. The sun often and the moon always obscured at the rising and setting, and the horizon all day long dusky....

The effects it has had on humane bodies (although I do not believe they have all immediately been caused by the earthquake) have (yet) been various: such as foolishness (but not to any great degree), madness, dulness, sottishness, and stolidity everywhere: hypochondriack, melancholick and cholerick distempers. Every-day fevers have been common, with many continual and tertian: malignant, mortal and dangerous ones in a great number, with deliria and lethargies. Where there has been any infection caused by the natural malignity of the air, infinite mortality has followed. The smallpox has made great destruction among children.”

Thus we find in Sicily a great disturbance of soil followed, as in Jamaica, by a great increase of local sickness, and by an atmosphere visibly charged with products of the earthquake for months after. This is a nearer source than the Jamaican for the British influenza of Oct.-Nov. 1693,—nearer in time, if that be any advantage for the theory, nearer also in place. There are, however, no intermediate stages to connect the influenza on the northern edge of the European continent with the disturbance of soil and the miasmata arising therefrom in Sicily and Calabria. If there had been any such dry fog as spread all over Europe from the Calabrian earthquake of January, 1783, it would have been a help at least to the imagination in bridging over a gulf of space and time.

As to the interval of time, it should at all events be kept in mind that the same difficulty has to be reckoned with in any hypothesis of influenza and in every great historic instance. In the instance still before us, the infection began in England, according to Molyneux, in October, 1693, and was in Dublin a month later. But we must assume it to have been in the air for some time before it became effective upon mankind. Influenza has been observed, with curious uniformity, to attack the horses, say of London, of Plymouth, of Edinburgh, or of Dublin (as on the occasion before this, 1688) two months or more in advance of the inhabitants of the respective places; and if it had waited, so to speak, for two months before it showed its effects upon men, it may have waited equally long, or longer, before it showed its effects upon horses. That would give at least four months; and then we know, from such an influenza as that of 1743, that there may be weeks, perhaps months, between its prevalence in Naples, Rome or Milan, and its prevalence in London or Edinburgh, and, from the influenza of 1693 itself, that it was a month later in Dublin than in London. An earthquake in Sicily on the 9th of January, 1693, with effects there for months after upon the water, the air, and the prevalent diseases, is not excluded by lapse of time from being a vera causa of an influenza in England in October of the same year, and in Ireland in November. The sort of proof which most men desire, a proof such as we rarely get, and one that is suspiciously neat when we do get it, would be to find an influenza in Sicily and Calabria following the earthquake, and to trace the same step by step over Europe. But the miasmatic sickness in the countries of the earthquakes was not influenza, so far as is known; and there was no epidemic catarrh, so far as is known, in any other part of Europe but the British Isles and the neighbouring shores of the North Sea.

V.

Molyneux, who recorded with a good deal of circumstance the influenza of 1693, is the principal authority, along with Dr Walter Harris, of London, for another influenza in 1688, seemingly peculiar to the British Isles. Its effects can be discovered with the utmost certainty in the London bills of mortality for two or three weeks at the end of May and beginning of June, and it is mentioned as “the new distemper” in letters of the time. Is it possible to find an earthquake for it? Webster’s note is: “in the same year with an eruption of Vesuvius, after a severe winter and earthquakes”—which is somewhat general. Turning to Evelyn’s diary, where these matters are often recorded, we find, in the very weeks when the influenza was at a height in London, this entry: “News arrived of the most prodigious earthquake that was almost ever heard of, subverting the city of Lima and country in Peru, with a dreadfull inundation following it”—as if the influenza and the news of the earthquake had reached London at the same time. This was the earthquake of 20th October, 1687, which destroyed Lima, Callao and an immense district along the coast of Peru. The rocking of the earth was most violent, the sea retreated like a sudden immense ebb and filled again like a sudden immense flood, the effect of the commotion being felt on board ships a hundred and fifty leagues out in the Pacific. It was remarked that wheat and barley would not thrive in Peru after that earthquake[775]. Here was undoubtedly a great disturbance of soil and of subsoil, almost certainly attended with the discharge of effluvia or miasmata into the air, as in other great earthquakes. But the universal slight fever of the British Isles in the months of June and July, 1688, is remote from the earthquake of Lima in place; and, if it be a question of earthquakes at all, there are others nearer to it both in place and time, such as that in the Basilicata province of Naples in January, 1688, and the Jamaica earthquake, felt through all the island, on the 1st of March, 1688. The greatest of them all, that of Smyrna, on the 10th of July, was a few weeks too late for the hypothesis.

VI.

A continent so subject to earthquakes as South America might be expected, in this hypothesis, to have had some corresponding influenzas. It has indeed had influenzas, some of them peculiar to itself. The Western Hemisphere as a whole has, on several great occasions, had influenzas which were not felt in the Old World. Again, there are one or two instances in which the infection, while it spread widely over the table-lands of Bolivia and Peru, does not appear by existing testimony to have been carried north of the Isthmus. One of these was the influenza of 1720, as special to a region of South America as that of 1688 was to the British Isles. The account of it was given in an essay by Botoni ‘On the Circulation of the Blood,’ published at Lima in 1723[776]. He calls it catarro maligno; it was popularly known as fierro chuto or “iron cap.” It appeared at Cuzco in the end of March, or beginning of April, 1720, and was over about November. Four thousand are said to have died of it in the diocese of Cuzco, and it is said to have made so great a scarcity of hands that the first harvest after it was imperfectly gathered. It had all the marks of an influenza, with the addition of bleeding from the nose and lungs. It had also the grand characteristic common to influenza and epidemic ague: “the symptoms were so diverse and even contradictory that no correct diagnosis, or curative plan, could be fixed.” The Lima writer of 1723 says that it followed an eclipse of the sun on the 15th of August, 1719, having begun on the eastern side of the Andes, in the basin of La Plata, about that time, and travelled northwards and westwards, as the South American influenza of 1759 did.