It has been said that Noyon was suggested by Tournai, doubtless on account of their superficial affinities. But the likeness is merely in general aspect, the methods of construction being wholly different. At Tournai the apsidal transepts are vaulted upon transverse arches of great strength, and upon radiating semi-arches united where they meet by a ring of voussoirs set horizontally, and at their springing by vaults keyed into their mass, an ingenious arrangement which recalls the vaulting of the Salle des Capitaines over the porch of the monastery church at Moissac.
The combination of these arcs-doubleaux, which, in addition to the solidity of their independent structure, are strongly reinforced by the massive circular courses of the walls, is very peculiar, for it dispenses altogether both with auxiliary arches and with abutments. Tournai, therefore, cannot be held to have begotten Noyon, for here we have groined vaults, the intersecting arches of which demand the reinforcement of abutments either concealed or apparent to sustain the thrust of these vaults over the lateral arcs-doubleaux. The ingenious arrangement above cited had in no sense modified the methods of abutment followed by the architects of the twelfth century even after the adoption of the vault on intersecting arches. These, as will be remembered, consisted in buttressing the walls and piers of the nave by cross walls or by arches concealed beneath the roofing of the side aisles.
27. CHURCH OF TOURNAI, BELGIUM. EXTERIOR VIEW OF THE NORTH TRANSEPT TOWARDS THE SCHELDT
28. MONASTERY CHURCH AT MOISSAC. VAULT OF THE HALL KNOWN AS THE HALL OF THE CAPTAINS ABOVE THE PORCH
29. CHURCH OF TOURNAI, BELGIUM. INTERIOR OF THE NORTH TRANSEPT
We find at Soissons the first application of an architectural system, the special feature of which is the flying buttress.
The south transept of Soissons Cathedral was evidently suggested by Noyon. This is apparent in the adoption of the two-storied side aisle and in the semi-circular plan. But the method of vaulting common to both churches has a greater refinement at Soissons. Reduced to its simplest expression of strength by the attenuation of its skeleton, the vault still exercises its full thrust on those parts which rise above the upper gallery.