The ravages of the small-pox, wherever they make their appearance, are attended with a general calamity. Of these they pretend to distinguish above forty different species, to each of which they have given a particular name. If a good sort breaks out, inoculation or, more properly speaking, infection by artificial means becomes general. The usual way of communicating the disease is by inserting the matter, contained in a little cotton wool, into the nostrils, or they put on the clothes of, or sleep in the same bed with, such as may have had a favourable kind; but they never introduce the matter by making any incision in the skin. This fatal disease, as appears from the records of the empire, was unknown before the tenth century, when it was perhaps introduced by the Mahomedans of Arabia who, at that period, carried on a considerable commerce with Canton from the Persian gulph, and who not long before had received it from the Saracens, when they invaded and conquered the Eastern Empire. The same disease was likewise one of those blessings which the mad crusades conferred upon Europe; since which time, to the close of the eighteenth century, not a hope had been held out of its extirpation when, happily, the invaluable discovery of the cow-pock, or rather the general application of that discovery, which had long been confined to a particular district, has furnished abundant grounds to hope, that this desirable event may now be accomplished. In some of the provinces the lower orders of people are said to be dreadfully afflicted with sore eyes, and this endemic complaint has been supposed to proceed from the copious use of rice; a conjecture, apparently, without any kind of foundation, as the Hindus and other Indian nations, whose whole diet consists almost exclusively of this grain, are not particularly subject to the like disease: and in Egypt, both in ancient and modern times, the opthalmia and blindness were much more prevalent than in China; yet rice was neither cultivated nor known in that part of Africa until the reign of the caliphs, when it was introduced from the eastward. The disease in China, if prevalent there, may more probably be owing to their living in crowded and low habitations, wherein there is a perpetual smoke from the fire, from tapers made of sandal wood dust employed for marking the divisions of the day, from the general use of tobacco, and from the miasma or noxious vapours exhaling from the dirt and offals which are collected in or near their habitations. The organ of sight may also be relaxed, and rendered more susceptible of disease, by the constant practice of washing the face, even in the middle of summer, with warm water. I must observe, however, that in the course of our long journey, we saw very few blind people, or persons afflicted with sore eyes.