object rather than an incident of the plan from which the structure proceeds. Without reference to its scale, the design for the Cathedral of Albany confesses the limitations that have been relaxed for the Cathedral of New York, and that render it unavailable as a direct model. These appear mainly in the interior, but, as we shall presently see, they affect the exterior design as well. As it was in the beginnings of the art of building, so now stone remains the material of monumental structures. In durability it is rivalled, if it be rivalled, by metal alone, and such experiments as the flèche of Rouen and the tower of Paris have not yet convinced mankind of the possibility of a monumental metallic architecture. Timber remains the most acceptable substitute, but timber in a cathedral is plainly a substitute, and monumental architecture admits no substitutes in the structure of a great building. A stone ceiling must be regarded as an indispensable requisite of a true cathedral; and although very impressive and noble cathedrals still exhibit wooden ceilings, they so far come short of fulfilling the idea of a cathedral, and the antiquarians are pretty well agreed that the purpose of the builders was to make their ceilings as durable as their walls, and that they failed to carry out their purpose either through lack of means or through doubt of their own ability to construct stone ceilings. Considering the elaborate expositions of construction in the true timber roofs of the English Gothic, the boarded ceilings of Ely and Peterborough were plainly makeshifts, and equally a makeshift would be the wooden ceiling, of trefoil section, hung to the timbers of the roof and concealing its construction, which Mr. Richardson designed for the Albany Cathedral. We come here rather unexpectedly, upon the question of “style.” If a vaulted ceiling be so eminently desirable in a purely monumental building as to amount to an architectural necessity, it is equally clear that the groined vault--that is to say, the vault formed by the [Illustration: GROUND-PLAN.]