On the 2nd February 1829, Jonathan Martin, a brother of the apocalyptic painter, John Martin, and a religious maniac, hid himself during evening service behind the tomb of Archbishop Greenfield in the north transept, and when the church was shut up for the night set fire to the choir. The flames were not extinguished until the stalls, the organ, and the vault had been entirely destroyed. The actual stonework and carving of the choir were considerably injured, and the glass of the great east window itself only just avoided destruction. Martin escaped through a window of the transept, but was quickly captured, and discovered to be insane. The restoration, carried on by Smirke, was begun in 1832, and on the whole was fairly done. At any rate, the authorities of the minster may console themselves with the knowledge that it was absolutely necessary. The stalls were a reproduction, as exact as possible, of the old woodwork, but the design of the throne and pulpit are original, and not successful. The cost of the restoration was L65,000, most of which was contributed by subscription. Timber, to the value of L5000, was given by the State, and Sir Edward Vavasour, following the example of his ancestor of the fourteenth century, supplied the stone. Another fire broke out on the 30th May 1840. It began in the south-west tower, and is said to have been caused by some workmen who were repairing the clock. The whole tower, excepting its shell, including the bells, was destroyed, and the fire was not extinguished until the wooden vault of the nave had been burnt. The restoration on this occasion cost L23,000, and was finished in a year, under the superintendence of Sydney Smirke, son of the former restorer. In 1871 the south transept was discovered to be in a dilapidated, and, indeed, a dangerous condition, and the advice of Street was asked on the question of restoring it. In his report he stated that the design of the clerestory, constructed as it was of two thin walls, was not strong enough for the weight it had to support, even though the vault was of wood. The whole wall of the transept had given way, and the clerestory, in particular, was in a very bad condition. It became necessary, therefore, to rebuild the side walls of the clerestory and the flying buttresses under the steep roofs of the aisles, to remove the heavy slates from the roof, and to renew the pinnacles. On investigation, it was discovered that the inside portion of the walls had been made up of stone chippings without cement. It is curious that builders in the thirteenth century, whose system of ornament was most profuse and thorough, often scamped the more important details of structure. At Peterborough, no less than at York, instances have been discovered of what would, in these days, be called jerry-building.