[13] York, Lichfield, and Lincoln, are the cathedrals distinguished by the possession of three towers. [14] For illustrations consult the Glossary under _Pier_. [15] For illustrations consult the Glossary under _Base_. [16] For illustrations consult the Glossary. [Illustration: {SCULPTURED ORNAMENT FROM WESTMINSTER ABBEY.}] CHAPTER V. GOTHIC ARCHITECTURE.--ENGLAND. ANALYSIS OF BUILDINGS (_continued_)--OPENINGS, ROOFS, SPIRES, ORNAMENTS, STAINED GLASS, SCULPTURE. _Openings and Arches._ The openings (_i.e._ doors and windows) in the walls of English Gothic buildings are occasionally covered by flat heads or lintels, but this is exceptional; ordinarily they have arched heads. The shape of the arch varies at all periods. Architects always felt themselves free to adopt any shape which best met the requirements of any special case; but at each period there was one shape of arch which it was customary to use. In the first transitional period (end of twelfth century) semicircular and pointed arches are both met with, and are often both employed in the same part of the same building. The mouldings and enrichments which are common in Norman work are usually still in use. In the E. E. period the doorways are almost invariably rather acutely pointed, the arched heads are enriched by a large mass of rich mouldings, and the jambs[17] have usually a series of small columns, each of which is intended to carry a portion of the entire group of mouldings. Large doorways are often subdivided into two, and frequently approached by porches. A most beautiful example occurs in the splendid west entrance to Ely Cathedral. Other examples will be found at Lichfield (Fig. 1) and Salisbury. It was not uncommon to cover doorways with a lintel, the whole being under an archway; this left a space above the head of the door which was occupied by carving often of great beauty. Ornamental gables are often formed over the entrances of churches, and are richly sculptured; but though beautiful, these features rarely attained magnificence. The most remarkable entrance to an English cathedral is the west portal of Peterborough--a composition of lofty and richly moulded arches built in front of the original west wall. A portal on a smaller scale, but added in the same manner adorns the west front of Wells. As a less exceptional example we may refer to the entrance to Westminster Abbey at the end of the north transept (now under restoration), which must have been a noble example of an E. E. portal when in its perfect state. [Illustration: FIG. 16.--LANCET WINDOW. (12TH CENTURY.)]