We come now to the night of the mysterious expedition of Jasper and Durdles, when they climb the Cathedral Tower in the moonlight, and when Durdles lies in a drugged sleep on the floor of the crypt. Jasper has been very active during this interval. How has his time been spent? His first business, after possessing himself of the key of the crypt, must have been to search in the bundle carried by Durdles for the key of the Sapsea monument. We have repeatedly been told of his interest in the bundle, into which (see chapter iv.) he had seen Durdles drop this particular key. The inscription had been placed on the monument, but we are to understand that the key had not yet been returned to the Mayor. Having secured this key, Jasper leaves the building, and by some means which can only be conjectured conveys quicklime to the monument, and places it in readiness in the empty space. He may have gone back to the yard-gate where Durdles had showed him the mound of lime, but this would have been a very risky proceeding, as the ‘hole in the city wall’ occupied by Durdles was beyond Minor Canon Corner, the Monks’ Vineyard, and the Travellers’ Twopenny. Even in the dead of night, sharp eyes in the lodging-house (Deputy’s, for instance) might have seen a man go by wheeling lime in a barrow or carrying it in a sack. It is far more probable that the lime was found nearer to the cathedral. It has been suggested, further, that Jasper, while away from Durdles, took a wax model of the key of the crypt, which also opens the door at the top of the steps leading from the crypt to the cathedral. The Dean (it is presumed by Professor Jackson) has already entrusted him with another key, that of the iron gate which gives access to the Tower. We are told that Durdles ‘bears the close scrutiny of his companion in an insensible way, although it is prolonged while the latter fumbles among his pockets for a key confided to him that will open an iron gate, so to enable him to pass to the staircase of the great Tower.’ Visitors to cathedrals to-day usually find that the key of the tower staircase is in charge of the chief verger, and Jasper would have no difficulty in obtaining a loan of it from this functionary for one night, though hardly for a longer period, as visitors would be coming and going.