This is a localized influenza in a country of earthquakes. But the two great earthquakes in 1719 are not South American. They both happened in July: one along the coast of Fez and Morocco, which ruined many villages and a part of the city of Morocco (there is also a later disturbance in the Azores in December, followed by the upheaval of a new island), the other in North China. Here we have the choice of following the “aer inimicus” of Lucretius either from China or from the African coast; and if it be the case that the influenza began in the latter part of the year 1719 in the basin of the La Plata, to cross the Andes next year, it may seem, in this hypothesis, that a course from east to west, bringing the infection across the Atlantic from Africa, is to be preferred to a course from west to east, bringing it across the Pacific from North China. In either case there need be no difficulty in finding local clouds of miasmata. Some traces of the corresponding great earthquake in China were found in November of the following year, by Bell, an English traveller who crossed from Moscow to Peking:
“Jumy,” he says, “suffered greatly by the earthquakes that happened in the month of July the preceding year [1719], above one half of it being thereby laid in ruins. Indeed more than one half of the towns and villages through which we travelled this day had suffered much on the same occasion, and vast numbers of people had been buried in the ruins. I must confess it was a dismal scene to see everywhere such heaps of rubbish[777].”
The atmospheric effects of Chinese earthquakes have been pictured since medieval times, in obviously superstitious colours; and there are reasons why a great disturbance of soil in that country should produce remarkable miasmata. The surface soil of China is peculiar in having the bodies of the dead dispersed at large in it, insomuch that excavations for the foundations of houses, or for roads and railway cuttings, can hardly be made without the constant risk of exposing graves[778].
If the soil of China is peculiar in one way, that of the West Coast of Africa is peculiar in another. Without entering on the large question of “malaria” in each of them, I shall take an old illustration of the miasmata of the West Coast of Africa as a cause of dengue-fever, a disease curiously like influenza in its symptoms, and like it also in its occasional wave-like dispersion over wide regions. The authority is Dr Aubrey, who resided many years on the coast of Guinea, saw much of the slave-trade, and wrote a very sensible book in 1729, called ‘The Sea Surgeon, or the Guinea Man’s Vade Mecum.’ He describes quite clearly the fever which was long after described by West Indian physicians as dengue, or three-days’ fever, or break-bone fever, including in his description the characteristic exanthems of it and the penetrating odour of the sweat. He gives also, in clinical form, a series of cases on board the galley ‘Peterborough’ in December, 1717, which are exquisite examples of break-bone fever. This disease, he says, “many times runs over the whole ship, as well negroes as white men, for they infect one the other, and the ship is then in a very deplorable condition unless they have an able man to take care of them.” But the original source of infection, he believed, was the fogs that hung at nightfall over the estuaries of the rivers; and he gives an experimental proof, remarkable but not quite incredible, of the poisonous nature of the miasmata:
“But to let you see the evil, malevolent, contagious, destructive quality of those fogs that fall there in the night, and how far they are inimical to human nature, I will tell you of an experiment of my own. I made a lump of paste with oat-meal somewhat hard, and about the bigness of a hen’s egg, which was exposed to the fog from twilight to twilight, i.e. from the dusk of the evening till daybreak in the morning; after which I crumbled it, and gave it to fowls, which we had on board, and soon after they had eaten it, they turned round and in a kind of vertigo dropt down and expired.”
A great mortality in Guinea in 1754 or 1755 was ascribed by Lind, the least credulous in such matters, to “a noxious stinking fog[779].”
What the alternations of heat and chill, of moisture and drought, produce ordinarily in the way of miasmata, the same, we may suppose, is produced on the great scale, as a phenomenon at some particular time and place, by one of those cataclysms which break the surface of the earth or the bed of the sea, lower or raise the level of wells and springs, and fill the air with particles of dust or vapour which may overhang the locality for months and visibly disperse themselves to a great distance. Nothing relating to miasmata in the air need be hard for belief after the wonderful diffusion and permanence in the atmosphere of the whole globe, for two years or more, of finely divided particles shot up by the earthquakes and eruptions of Krakatoa in the Straits of Sunda on the 27th and 28th of August, 1883[780].
A theory of influenza constructed from such generalities as those of Boyle, Arbuthnot and Webster will have attractions for many over the theory that influenza is always present in some remote country and becomes dispersed now and then over the world by contagion from person to person: it will have superior attractions, for the reason that influenza is a phenomenal thing which needs a phenomenal cause to account for it. But if anyone were to attempt to fit each historic wave of influenza with its particular earthquake, or to find the precise locality where clouds of infective matter had arisen, or the particular circumstances in which they arose, he would certainly find his fragile structure of probabilities pulled to pieces by the professed discouragers and depravers. I make no such attempt; but I am not the less persuaded of the direction in which the true theory of influenza lies.
Influenza at Sea.
There is no point more essential to a correct theory of influenza than to find out in what circumstances it has occurred among the crews of ships on the high seas. If it be true that a ship may sail into an atmosphere of influenza, just as she may sail into a fog, or an oceanic current, or the track of a cyclone, then the possible hypotheses touching the nature, source, and mode of diffusion of influenza become narrowed down within definite limits.