176 THE PLAGUE.

at that period, rather than diminished. Some persons were of opinion, that the infection maintained its virulence till the last ; that the decrease of mortality did not originate from a decrease of the miasma, but from a decrease of population, and a consequent want of subjects to prey upon ; and this indeed is a plausible idea ; but admitting it to be just, how are we to account for the almost invariable fatality of the disorder, when at its height, and the comparative innocence of it when on the decline ? for then, the chance to those who had it, was, that they would recover and survive the malady.

The old men seemed to indulge in a superstitious tradition, that when this peculiar kind of epidemy attacks a country, it does not return or continue for three or more years, but disappears altogether, (after the first year,) and is followed the seventh year by contagious rheums and expectoration, the violence of which lasts from three to seven days, but is not fatal. Whether this opinion be in general founded in truth I cannot determine ; but in the spring of the year 1806, which was the seventh year from the appearance of the plague at Fas in 1799, a species of influenza pervaded the whole country; the patient going to bed well, and, on rising in the morning, a thick phlegm was expectorated, accompanied by a distressing rheum, or cold in the head, with a cough, which quickly reduced those affected to extreme weakness, but was seldom fatal, continuing from three to seven days, with