‘The crypt,’ says Raoul Boutrais, in his Latin poem in praise of Chartres (1624), ‘lies darkling in a hollow of the earth, resting on many an arch, as long and as wide as is the whole church above it. A dim religious light struggles through the deep-set windows. Enter and behold a sacred altar. Your being is filled with a mysterious awe as you descend. Then by the light of a thousand torches the sacred place becomes visible. The smoke of fragrant incense rises from the altar. Priests move to and fro performing their sacred office before the image of the Virgin. Many offerings of gold and silver, in token of granted prayers, hang at the shrines. ‘We pass into recesses dug deep within the earth, and are conscious of a strange emotion. Here was the first origin of the church, when the early Christians sang their hymns in these dark places to escape the cruel punishments of the Prefect Quirinus, and yet undaunted by the cross, the sword, the fire of his mad rage. He snatched this heroic band from their Christ, and flung their mangled bodies into the deeps of a well. Still may be seen the well, fenced about that none may fall therein; for, ’tis said, that some have fallen. And it was not only to sing their hymns that the Christians assembled here, but here they passed their lives for fear of persecution. Therefore in their hiding they dug a well that they might have to drink.’ It is evident from this and other passages that the famous well was in existence in the first half of the seventeenth century; but shortly afterwards ‘it was covered up by reason of the vapours with which it filled these subterranean places.’[12] It was covered up, and the site of it deliberately falsified when the sanctuary of the Virgin was decorated and the transverse wall between the real site of the well and the altar was built. After the alterations which were then made were completed (1671), the public was informed that the well was now under the step of the new altar, so that those who knelt there, and had a particular devotion to the Martyrs’ Well, appeared to be rendering homage to the Virgin. The statements of the historians to the effect that the well was behind the altar were explained away by the very canon who had superintended the filling up of the well, for he made the misleading assertion that the altar itself had been moved back in the course of the alterations. He was believed. When in the nineteenth century efforts were made again and again to find this well, they were always made on the assumption that the altar had been so moved. The cynical precept which warns us to be on our guard against the occasional untrustworthiness of those who never lie was forgotten. It was not till M. René Merlet’s pamphlet, _L’Ancienne Chapelle de Notre-Dame-de-Sous-Terre_, appeared in 1900 that investigations, based on historical research and archæological acumen, began to be prosecuted, and were before long crowned with success. Boutrais’s words are now once