Force of habit determined the application of the round form to towers of the twelfth century; but it is evident that a square plan was preferred, even so early as the tenth century, and such a form was in course of time rendered necessary by the development of the founder's art, and the increase in the dimensions of bells at the beginning of the twelfth century. Besides the great bells which proclaimed the hour of prayer to a distant flock, small bells were in use to regulate the religious exercises of the clergy. They are called in the Latin texts _signum_, _schilla_, _nola_; in French _sin_, _esquielle_, _eschelitte_; from the beginning of the tenth century they were placed in the campaniles which crowned the domes. The Italian word _campanile_ has the force of the French terms _tour_, _clocher_, _beffroi_ (or the English tower, steeple, belfry). But the denomination _clocher_ has a general application to all pyramidal structures rising above the roof of a church. The belfry was a tower, in most cases isolated, which contained the bell destined to sound the curfew and tocsin, and to call the burghers to civic assemblies. Like the belfry, the Italian campanile is generally an isolated building, but it is usually placed in the near neighbourhood of a church. Among the most famous _campanili_ are those of Florence--begun in the fourteenth century, on the plans of Giotto,--of Padua, of Ravenna, and the famous leaning tower of Pisa. [Illustration: 83. STEEPLE, VENDÔME (TWELFTH CENTURY)] In France the term campanile has a more general application, and is given to the little pierced arcaded turrets which, in many churches, crown the walls of the façade and shelter small bells. [Illustration: 84. GIOTTO'S TOWER AT FLORENCE] The most ancient belfries of the original provinces of France have great analogies with Byzantine monuments as to form, even when differing in detail. One of the most remarkable of these is the tower of St. Front at Périgueux, which seems to date from the first years of the eleventh century. It marked the sepulchre of the Saint, and apparently embraced two bays of the original three-aisled Latin church of the sixth century, evident traces of which have been discovered to the west of the great domed building of later times. The tower of St. Front is composed of three square stories, diminishing on plan as they rise, and crowned by a conical dome, resting upon a circular colonnade, the columns of which vary in height and diameter, and owe their origin to Roman examples in the neighbourhood.[29] [29] _L'Architecture Romane_, by Ed. Corroyer; Paris, Maison Quantin, 1887.