As to the opinion of pestilential vapours arising out of the earth, though we are assured that people have been suddenly killed by explosions, probably of the electrical kind, or by lightning issuing from under their feet, yet we are not furnished with any well authenticated accounts of a _plague_ having arisen from any such cause. About 19 years ago a violent fever raged epidemically through a small district in the north of Scotland, which was said to have originated in the following manner. Some young men having heard that a certain place in their neighbourhood had, in the time of a plague been a burial ground, took into their heads to dig into it. They did so, and one of them immediately fell sick, but recovered. The father of two of the young men, exceedingly displeased at the conduct of his sons, and apprehensive of the consequences, filled up the hole they had dug in the ground, soon after which he fell sick and died, and the fever continued to rage in the neighbourhood for some time. The mother of another of the parties concerned also died, and boils broke out on various parts of the bodies of the sick. This was the account given in some of the news-papers of the time, and had the matter been thoroughly investigated and attested, would have been decisive in favour of pestilential contagion being capable of taking up its residence in the earth. As it stands at present, it can only draw our attention to what may happen in another case, should any similar one occur.[84] [84] Though the writer of this Treatise was not at that time on the spot where this event took place, yet he has as good evidence as any one can have of what has not fallen under his immediate inspection, that these graves were opened, that the father of one of the young men died; and the mother of another, and one of the young men himself was taken ill with the eruption of boils on some parts of his body; but whether there was any person previously affected with fever in the neighbourhood from whom it might have been derived, or any thing which might have strongly predisposed those people to it, is unknown. It is indeed no easy matter to discover who was the first person affected with an epidemic, as no body chooses to own that either they, or any of their relatives were the authors of mischief, however involuntary, to the community. M. Chaptal, however, in his Elements of Chemistry, has some curious, as well as useful observations on the propriety of burying bodies in a sufficient space and at a sufficient depth; and on the accidents which may arise from opening vaults and burying grounds. An instance of this he gives of the ground of a church in Paris being dug up, which emitted a nauseous vapour, affecting several people in the neighbourhood.