Navigating a Cathedral Part II

Let’s next look at the area above the nave.  What we would call a ceiling is called a vault – because it is usually curved.  Early churches had a timber vaults and they would be painted with beautiful designs or images.

Timber vaults were prone to fire, though, so the builders learned to make stone vaulting. 

Churches and cathedrals were often “remodeled” – after a fire, for example, or when new styles became all the rage, or when there was a new bishop.  But because these are such large buildings, the remodeling did not simultaneously occur in all sections (much as today we may remodel our kitchen, but not the bathroom).  So, it is not uncommon to see two different vaulting styles right next to each other.

Above we are looking at a crossing tower, with a wood vault in the center.  The four sides around it have stone vaulting, but the designs are different.  This inconsistency was not considered a problem. 

Plain stone vaulting was soon decorated with thin stone “ribs.”  Early ribs were useful in covering “wobbly groins” – where the intersection of two tunnels was not quite smooth.  Masons soon discovered these ribs had the potential to create beautiful patterns. 

Ribs can be categorized as follows:

  • Transverse ribs – do not cross each other. They visually take us to from one wall to its opposite wall.
  • Diagonal ribs – cross each other, creating an x. Their purpose is to cover groins and highlight the architecture of the vault.
  • Tierceron ribs – are secondary long ribs. They are decorative.
  • Lierne ribs – are short ribs, and are also decorative
  • Ridge ribs – are decorative ribs that goes down the center of the vault. On the right-hand side, you can see a photo of Bristol Cathedral’s vault, which unusually has three ridge ribs.

In late medieval times, the English masons invented what we call “Fan Vaults.”  You will not find these much – if at all – on the European Continent.  Fan vaults are structurally different from rib vaults in that fan vaults are stone sculptures created on curved stones, then assembled as one would assemble an igloo.

We have spent a lot of time looking at vaults, and before we return to our floor plan we need to look at the interior elevation.

On the right, you see a drawing of what we call a bay.  This is the basic architectural unit of a great church.  It is a composition on three levels between the distance of two supporting piers or columns.  The photo on the left is of the nave at Ely Cathedral.

The lowest level – a “first floor” – has two piers or columns joined by an arch.  In front of it is the nave and behind it the aisle. 

The second level is called a gallery or a triforium, and we will see the difference shortly.

The top level is called a clerestory.  This level provides the primary source of light during the day.

In England, only one parish church has three levels (St Mary’s Redcliff in Bristol) and only one cathedral – Bristol Cathedral – has two levels. The rest have this three-level composition.

Let’s look at each level individually.