aisles, was extended by three bays eastwards,[218] the style having a resemblance to advanced First Pointed work, with some peculiarities of detail, exhibiting probable French influence from Upsala.[219] The triforium consists of plain, chamfered, semicircular arches and jambs in three orders; the clerestory has simple pointed windows, moulded on sconsion, but without cusps. A vaulting shaft is carried up between the piers.[220] The east end of the cathedral is of First Pointed period, and the great east window fills the whole space available.[221] The three western doorways and the pointed doorway in the south transept are later than the choir;[222] they present the finest examples in Great Britain of the use of coloured stones in the construction.[223] The north doorway and the central doorway of the west front have the colours arranged in concentric rings in the arches, red and yellow alternating. In the south doorway the same colours radiate and alternate, and in the doorway of the south transept the red and yellow stones are arranged chequerwise.[224] They are among the most charming portions of the edifice, and are unique in Scotland. The upper part of the gablet over the centre doorway is of the seventeenth century, and bears the shield of Sir George Hay of Kinfauns, who rented the lands of the bishopric about the beginning of the seventeenth century, the crozier being added to the shield in connection with the lands of the see.[225] The tower has been considerably operated upon in modern times; the old wooden spire was destroyed by lightning in 1671. The parapet and pinnacles are modern, as also the pointed and slated roof--the lower part being of considerable age. The part within the roof of the church is apparently of transition date; the upper part, with the large pointed windows, is probably of fifteenth-century work.[226] There were originally beautiful specimens of wood-work; the canopy over the bishop's throne has disappeared.[227] The tower contains four bells, three of which were given by Bishop Maxwell (1526-1540). The cathedral does not appear to have suffered during the Reformation period, but an attempt made by the Earl of Caithness to destroy it in 1606, during the rebellion of Earl Patrick Stewart and his son, was prevented by the intervention of Bishop Law (sacred be his memory!).