The custom of burying in churches, and of depositing the bones of dead bodies in charnel houses, gives M. Navier occasion to make observations upon this two fold abuse; and in a second dissertation, which is a sort of appendix to the first, he, with great reason, declares against burying in churches, which is too frequently permitted under the specious pretext of raising thereby a revenue for the support of the fabrick. He observes, that this custom of burying in churches was never allowed before the ninth century; and that ever since it has been allowed, it has, from time to time, produced unfortunate consequences; several of which he relates, both ancient and modern, that have happened at Chalons, at Montpelier, at Paris, and in foreign countries. As the earth which is thrown up by digging new graves, is impregnated with a great quantity of corrupt particles, conveyed into it, by the bodies before interred therein. It is not at all surprising, says he, that such unlucky effects should ensue; for if the bodies of dead animals left in the open air, often occasion contagious diseases, though the free air to which they are exposed is continually carrying off, and, as it were, sweeping away those putrid impurities which arise from dead bodies, by degrees, as they become corrupted, what have we not to fear from churches where great numbers of people are interred? It is these poisoned particles, he adds, with which the earth is impregnated, that has caused the death of great numbers of grave diggers, even upon their opening ground where no vestige of any dead body was to be found; and it is for this reason, that they are generally obliged to dig a grave at several intervals; for if you ask them why, they will tell you, that they feel themselves, as it were suffocated; if they continue at it for any long time; and their breathing in these infected vapours, is what makes such men generally but short lived. According to M. Navier, the most effectual remedy for this abuse, would be, not to permit any, or but very few persons to be buried in churches; and when it is allowed, to slack a large quantity of lime upon the body, there being no more certain method for destroying it speedily, and as one may say, before it can pass through any one degree of corruption. But, as in spite of all these precautions, the air in churches may often be a little vitiated, M. Navier, proposes a very easy method for restoring it to its natural purity, which, is to take out, in the day time, some of the upper panes of the glass windows, near the vaults; which little openings cannot render the church too cold, and at the same time will make a free communication between the external and internal air.