The free-standing crosses, in which the outline of the stone corresponds with the outline of the cross, are the most highly developed type of Celtic sculptured monument of the Christian period, and are therefore presumably the latest, with the exception of those of the decadent period just before and after the Norman Conquest. The free-standing crosses show the influence of the architect rather than that of the monkish scribe who embellished the early Irish and Hiberno-Saxon illuminated MSS. The sculpture is less flat, and the mouldings round the panels of ornament are more elaborate than on the earlier erect cross-slabs. The free-standing crosses also, instead of being monolithic, are constructed of two or more separate pieces of stone fixed together by means of mortice and tenon joints. In the larger of the High Crosses of Ireland the base forms one block, the shaft another, the head a third, and sometimes the top arm a fourth. [Illustration: Front] [Illustration: Back Cross at Neuadd Siarman, near Builth, Brecknockshire Scale ¹/₁₂ linear] The High Crosses of Ireland are in most cases associated with a characteristic set of ecclesiastical structures consisting of a Round Tower and several small churches. This class of monument consequently belongs to the time when the artistic talents of the Celtic monks, which had been previously entirely absorbed in illuminating MSS., was directed into the new channel of architecture. The High Cross of Muiredach[381] at Monasterboice, Co. Louth, and that of King Fland[382] at Clonmacnois, King’s Co., are proved by the inscriptions upon them to have been erected during the first quarter of the tenth century. There is such a general family likeness between most of the High Crosses of Ireland that they are probably all of about the same date. There is a peculiarity in the design of some of the High Crosses of Ireland which should not pass unnoticed, namely, the semicircular projection in each of the four hollows between the arms.[383] In a stone cross these projections have no use or meaning, but in the metal crosses of the same period projections of this kind serve to disguise the rivets by means of which the metal plates on each side of the cross are held together.[384] From this it would appear that the art of the worker in metal to some extent influenced the sculptors by whom the stone crosses were made. Some of the Cornish crosses have triangular projections in a similar position, giving an appearance not unlike the cusping in Gothic window tracery. [381] Petrie’s _Christian Inscriptions in the Irish Language_, vol. ii., p. 66. [382] _Ibid._, vol. i., p. 43. [383] As on the crosses at Monasterboice, Co. Louth, and Durrow, King’s Co. [384] As on the Cross of Cong in the Dublin Museum, and on the pectoral cross of St. Cuthbert in the Library of Durham Cathedral. [Illustration: Cross at Nevern, Pembrokeshire Scale ¹/₂₄ linear]