Precisely the same order was followed by the influenza twenty years after: it began in North America in March, 1781, and, says Webster, spread over that continent; it appeared in the East Indies in October and November, 1781, and on the eastern confines of Europe in January, 1782, having been traced from Tobolsk, made a slow progress westwards, and was at its height in London about the end of May or beginning of June. Assuming, says Webster, that the American influenza of 1781 had been continuous with the European of 1782, it must have “passed the Pacific in high northern latitudes,” traversed Siberia and Tartary, and so reached Russia in Europe. In like manner, if the European influenza of 1762 were continuous with the American of 1761, it must have made the circuit of the globe in the same order, as if it were following the first impulse of the volcanic waves across the Atlantic from the coast of Portugal westwards, and so round the earth until it came back to Europe on its eastern frontier. So much may be fairly advanced on the ground of a particular set of facts. But then there were many other facts, both in 1761-62, and in 1781-82. Meanwhile let us take another instance of volcanic waves felt at Barbados six years before, on the same afternoon as the great earthquake of Lisbon.
II.
At Bridgetown, on the 1st November, 1755, Dr Hillary saw the peculiar flux and reflux of the water in the harbour from 2.20 p.m. to 9 p.m. and pronounced that there must have been an earthquake somewhere. The waves came at first at intervals of five minutes, and at last at intervals of twenty minutes. The day was calm, and the ships in the bay were not touched; but small craft lying in the channel over the bar were driven to and fro with great violence. There was no motion of the earth, and no noise. The distance from Lisbon was 3400 miles, the vibrations having taken seven and a half hours to reach Barbados. The one notable effect in the harbour of Bridgetown was that the water flowed in and out with such a force that it tore up the black mud in the bottom of the channel, so that a great stench was sent forth and the fishes caused to float on the surface, many of them being driven a considerable distance on to the dry land where they were taken up by the negroes[763].
It so happened that there was an epidemic catarrh prevalent at that very time all over the island of Barbados, chiefly among children, few or none of whom, white or black, escaped it. It had begun in October, says Hillary[764] (who chronicled the epidemiology very exactly), and continued into November, so that it both preceded and followed the great convulsion in the bed of the Atlantic, which destroyed Lisbon and tore up the mud in the harbour of Bridgetown, disengaging a great stench therefrom and poisoning the fish. Webster’s theory of a relation between earthquakes and influenzas provides for such discrepancies in the dates of each: it is probable, he says, that seasons, earthquakes and volcanic eruptions are themselves the effects of those motions and invisible operations which affect mankind, so that catarrh and other epidemics often appear before the visible phenomena of eruptions and earthquakes. In like manner, the chronicler of the earthquake of Lisbon in the Philosophical Transactions drew attention to the fact that there had been a remarkable drought for several years before, and that some of the springs near Lisbon were actually dried up at the time. That droughts precede earthquakes is perhaps the most instructive generality that has yet been reached as to the cause of the latter.
Let us see, then, whether any such remote antecedents, in a possible relation to the influenza epidemics, hold good for the island of Barbados. Hillary’s chronicle is sufficiently full to let us answer the question.
Following the seasons and prevalent maladies backwards from the influenza of children in October-November, 1755, we find a catarrhal fever all over Barbados in February of the same year, which “few escaped having more or less of.” The immediate precursor of that influenza had been a very definite constitution, eighteen months long, of a “slow nervous fever,” from February, 1753 to September, 1754, which corresponds in every respect to the “remittent” fever of nearly the same period in England and Ireland, described by Fothergill, Rutty, Huxham and Johnstone, and to the famous Rouen fever described by Le Cat. Hillary is clear that the “slow nervous fever” was not seen again so long as he remained in the colony (1758). Just before it began, there had been an influenza so general in December, 1752, and January, 1753, “that few people, either white or black, escaped having it,” and that, in turn, was preceded by a season of agues, which, says Hillary, “are never seen in Barbados now [1758], unless brought hither from some place of the Leeward Islands.”
So many influenzas in Barbados, and so many things possibly relevant to them among their antecedents. So also in New England, the influenza which seemed to follow the earthquake along the coast of Portugal on the 31st of March, 1761, had the same remittent and intermittent fevers among its antecedents.
In the winter and spring of 1760-61 there had been much fever in New England, which was believed to be malarious. Webster, however, says: “There is no necessity of resorting to marsh exhalations for the source of this malady. The same species of fever [as at Bethlem] prevailed in that winter and the spring following in many other parts of Connecticut where no marsh existed. In Hartford it carried off a number of robust men, in two or three days from the attack.... In North Haven it attacked few persons, but everyone of them died. In East Haven died about forty-five men in the prime of life, mostly heads of families. The same disease prevailed in New Haven among the inhabitants and students in college.” In Bethlem the sickness began in November, 1760, and carried off about forty of the inhabitants in the winter following. This was the fever, generally reckoned malarious, which preceded the influenza of April and May, 1761[765].
III.
The next great influenza, twenty years after, which was in America in the spring of 1781 and in Europe in the winter and spring following, will repay the same kind of scrutiny. There had been influenza here or there in Europe since the beginning of 1780, but no great epidemic of it; and in England, as elsewhere, there had been epidemic agues and dysenteries since that year, or the autumn before. The epidemic agues became worse in England in 1783, 1784, and 1785, appearing in places which had never been thought malarious. The whole period from 1780 to 1784 was remarkable for hot and dry summers and great earthquakes. Italy and Sicily were troubled by earthquakes to an unusual extent in 1780, 1781, 1782, and 1783; they were so frequent in 1781 that the pope ordered public prayers. The great earthquake of the period was in Calabria at half an hour after noon of the 5th of February, 1783, about six months after the great influenza of the period was over. Sir William Hamilton, the British ambassador at Naples, visited the numerous scenes of the earthquake in Calabria and Sicily in the first fortnight of May, 1783, and sent to the Royal Society an account of what he saw. At several places he found fever epidemic, part of it from the overcrowding and filth of the temporary barracks in which the people were living, part of it malarious from the damming of water by changes in the river beds. At Palmi the spilt oil mixed with the corn of the overthrown granaries, and the corrupted bodies, had a sensible effect on the air, which threatened an epidemic; at the village of Torre del Pezzolo an epidemical disorder had already manifested itself[766].