The use of pinnacles, considered independently of their ornamental purposes, is evident enough. It is obvious that a wall or pillar which has to resist the thrust of a vault or any other power exerted laterally, depends for its stability on its thickness, its solidity, and generally on its lateral strength. A material consideration, as affecting this solidity, is that of weight. The most frequent use of pinnacles by the French was to surmount the piers from which the flying buttresses sprang. To these piers weight and solidity were thus imparted, rendering them a sufficiently steady abutment to the flying arches, which in their turn abutted the central vaults. It must be understood that these expedients of buttresses and pinnacles were only employed to support the central roof of the nave. The vaults of the aisles were so narrow as not to require any elaborate system of abutments for their support—the ordinary thickness of the walls would have sufficed for that purpose; but they also had the advantage of the use of the supports designed for the larger vaults. As a general rule the English architects never hesitated to weight their walls so as to apply the resistance directly on the point required, and not only adorned the roofs of their churches with pinnacles, but raised towers and lanterns on the intersections on all occasions. The French, on the other hand, always preferred placing these objects, not _on_ their churches, but rather grouped around them, and springing from the ground. This, it is true, enabled them to indulge in height and lightness internally to an extent unknown in England. This extravagance proved prejudicial to the true effect even of the interior, while externally the system was very destructive of grace and harmony. A French cathedral is generally solid and simple, as high as the parapet of the side-aisles, but above this base the forest of pinnacles and buttresses that spring from it entirely obscure the clerestory, and confuse its lines. Above this again the great mass and simple form of the high steep roof, unbroken by pinnacles or other ornaments, contrasts unpleasingly with the lightness and confused lines immediately below it. This inconsistency tends to mar the beauty of French cathedrals, and even of their churches, though in the smaller buildings the effect is less glaring owing to the smallness of the parts. SPIRES. An easy transition leads from pinnacles to spires, the latter being but the perfect development of the former, and each requiring the assistance of the other in producing a thoroughly harmonious effect. Still their uses were widely different, for the spire never was a constructive expedient, or useful in any way. Indeed, of all architectural features, it is the one perhaps to which it is least easy to apply any utilitarian rule.