In the above general description of the cathedral, the probable dates of the various parts have been casually referred to. It is now proposed to explain more fully the dates we would assign to the different portions of the structure and the reasons for doing so. Dr. Skene has the following footnote[37]-- “One of the columns which supports the great tower of the Abbey Church has on the upper portion the inscription, ‘Donaldus O’Brolchan fecit hoc opus,’ and seems to think that that inscription fixes the name of the builder of the church. Messrs. Buckler, in their description of the architecture of the cathedral,[38] give the above inscription as reading, ‘Donaldus ornatum fecit hoc opus.’” The inscription is not now legible, but even if it were, it could give little clue to the date of the edifice. [Illustration: FIG. 994.--Iona Cathedral. View from North-West, showing Cloister Garth, Central Tower, &c.] [Illustration: FIG. 995.--Iona Cathedral. General View of Cathedral and St. Oran’s Chapel, from South-West.] There will probably be little difference of opinion regarding the antiquity of the east wall of the north transept (see Fig. 996). The character of the arches, shafts, and caps, even worn away as they are, is distinctly late Norman or transition. The small round headed windows in the recesses of the wide internal bays are also quite in keeping with that [Illustration: FIG. 996.--Iona Cathedral. East Side of North Transept.] style. The depth of the recesses on each side of the central arch, with its figure, which form a special feature, was rendered necessary by the extra width of the wall required (as will be pointed out further on) to admit of a passage in the thickness of the wall above. Almost all the rest of the church appears to be of a much later date, and to belong, with small exceptions, to the late fifteenth or early part of the sixteenth century. Part of the crossing, however, is probably older; but the other portions of the crossing seem to have been rebuilt at a late date, as the following indications show. The original arches of the north and west sides have no mouldings, but are only chamfered, and the caps, so far as visible, have an ancient character. The north arch has, at some period, been strengthened by the insertion of additional piers, and an additional arch within the then existing piers and arch (see Plan). The old arch is distinctly visible in the wall, and portions of the old piers are also exposed to view. [Illustration: FIG. 997.--Iona Cathedral. North Side of Refectory.]