“The aqueducts existing no longer, the sewers and privies were alike neglected, and produced serious and frequent sicknesses, which were more effectual in destroying the population than the arms of the barbarians. All the historians of these remote times, and particularly St. Gregory, in his Homilies, and the deacon John, in the Life of that saint, give a frightful picture of the city of Rome. The air became so vitiated that plagues and fevers of a malignant character continually carried on their ravages to such a point that Peter Damien, writing in the eleventh century to Pope Nicholas II., to intreat him to accept his resignation, alleged as the pretext the danger he ran every instant of losing his life by remaining in the town. “It was principally during the abode of the popes at Avignon that all which regards health was neglected at Rome, and some historians have not hesitated to attribute to this negligence the depopulation of the town, which was reduced in a little time to 30,000 inhabitants. “Things remained in this state to the end of the fourteenth century, an epoch at which the popes, resuming the ancient labours, restored things to their proper condition; a new title to glory of Leo X., who of all the popes was the one who occupied himself with this important object in the most especial manner. “It is, in part, to these precautions that we are to attribute the rapid increase of the population of Rome, which, from 30,000 souls, reached in a short time to 80,000; and it is a thing worthy of our attention that after the death of this pontiff the population quickly fell to the number of 32,000, because, according to the contemporary authors, everything having been neglected, the first calamities were renewed. “Happily for Rome this state of things did not continue long, because all successive popes, instructed, it appears, by the experience of ancient times, having carried on immense labours, and constructed fresh sewers, have given to the air of this city the necessary purity.” Italy presents instances, though comparatively modern, of the removal of disease by land drainage:—